Guide:Multiclassing Guide by Phantomsplit

This guide was initially in the form of a Reddit post shared on r/BG3Builds and r/BaldursGate3, and is being copied over to the community wiki. Some of the guide's formatting may reflect this transition.

This guide was written while Baldur's Gate 3 was still in early access. While we know that Larian will be making many changes to the D&D 5e rules, classes, races, feats, and spells including ignoring multiclassing ability score prerequisites, we do not know the full extent of rule changes at the time of writing. This guide is to establish a foundational understanding of D&D 5e rules on multiclassing so that you can respond to any rule changes by Larian should they emerge.

Introduction

D&D 5e rules for multiclassing can be found here for free. Larian may adjust these rules in BG3. Larian is already homebrewing several of the rules regarding race, class, and subclass options. Some D&D 5e builds may not work well in BG3. And BG3 may have some really good multiclassing builds that wouldn't be possible in tabletop. Until we know the exact details and to get people a basic understanding of the rules, I am going to assume that BG3 will be in line with D&D 5e except in areas we already know this will not be the case.

There are many posts out there with regards to D&D 5e multiclassing. This post will be unique in that it will account for the subclasses, races, and level cap which are found in BG3. But once again, we don't know all the details yet to plan a complete character builder, so I am treating any unknown features as though they work like in D&D 5e.

You can try to make your own D&D 5e multiclassed character using character creators like those on D&DBeyond. A free account I believe gets you 2 or 3 characters you can make at a time. An account that has not purchased any additional material will be very limited on what class, race, and subclass options you can pick. But you can dabble in multiclassing, pull up a character sheet for the character you made, and see how things work.

Opportunity Cost

It is difficult to "mess up" a D&D 5e character, but Multiclassing without a plan can be one way to do so. Multiclassing does not come for free. Every level you take in some other class, means one less level in your main class. It's up to you to weigh whether the trade-off is worth it. For example, in the first of the below builds the character will finish at Barbarian 9/ Fighter 3. Those 3 levels in Fighter grant some great features, and many people would say it's worth the multiclass. But is it worth losing the subclass feature, feat/ability score increase, and relentless rage that a barbarian gets between levels 10-12 in their main class? That's for you to decide. If you are going to multiclass, then do it with a plan in mind and always weigh the opportunity cost.

It's worth emphasizing that multiclassing can result in you losing a feat/ASI. Most classes only get feats/ASIs every 4 levels (fighters or rogues can get additional ones at 6th or 10th class level respectively). Missing out on one or more of these can be extremely detrimental to your character at higher levels.

Common Multiclassing Confusion and Pitfalls

I will not cover all the multiclassing rules. They are described in depth here with examples. The basics are that when you level up you can choose to increase the level in your existing class. Or you can take a level in a different class. So a second level character may be a Level 1 Fighter/Level 1 Wizard, getting most of the benefits of each class. You also will get the recommended ability point spread from the first class you chose. But I will provide emphasis to some common sources of confusion and pitfalls.

What do you get from your second class?

You get almost everything that your second class has to offer. The biggest outliers are the starting proficiencies. You do not get any additional saving throw proficiencies by taking first level in a second class. You only get armor, skill, and weapon proficiencies from your second class that are shown in the table found in the rules. If your second class has a subclass which grants proficiencies at first level, then you DO get those subclass proficiencies. For example some cleric subclasses grant heavy armor proficiency. If you multiclass into cleric and take one of those subclasses then you should get heavy armor proficiency.

The other big things that you do NOT get to stack from a multiclass are unarmored defense, extra attack, and uses of channel divinity. A 5th level paladin gets to make an extra attack when they take the attack action, and a 5th level barbarian gets to make an extra attack when they take the attack action. But a barbarian 5/paladin 5 does NOT get three attacks when they take the attack action (barring some external buff of some kind). Monk and barbarian unarmored defense do NOT stack, you get one or the other.

Class Level vs. Character Level vs. Spellcaster level

For the most part if you are trying to see what your character can or cannot do, you need to only look at the features granted by their level in each of their classes. The two main things that scale off Character Level are proficiency bonus and damage scaling from cantrips (0 level spells). There are other things that scale of character level, such as the Tough feat. But we are really getting into nuances here. Cantrip damage scaling and proficiency bonus are the big two. Spellcaster level is covered below.

Multiclassing Spellcasters (ignoring Warlocks)

Multiclassing spellcasters is the most complicated part. You determine your spells known/prepared (including cantrips) by looking at what spells you would know or prepare for each class with the Spellcasting feature. And you must use the spellcasting ability (Charisma, Intelligence, Wisdom) for the class which gave you that spell. The D&D 5e multiclassing rules provide examples of how this works.

However to determine the number of spell SLOTS you must determine your spellcaster level, and then use the caster level table provided in the rules (which is identical to the spell slot table for any full caster). So while a second level sorcerer would only have three spell slots of 1st level, and a third level paladin would only have three spell slots of 1st level, a sorc 2/paladin 3 does NOT have six spell slots of 1st level. This character's spellcaster level would be third. 2 spellcaster levels from sorc, and only 1 spellcaster level from paladin since paladins are "half-casters" (like rangers), so you divide the class level by two and then round down to determine the spellcaster level. This means the character would have three first level spell slots, and a second level spell slot. But they won't actually know any second level spells, meaning that the second level spell slot can only be used to upcast the first level spells that they actually know.

While the basic rules version of multiclassing don't cover Eldritch Knight Fighter and Arcane Trickster Rogue, they follow the same rules as Paladins and rangers except that EK fighter and AT rogues are 1/3 casters. Meaning you need to divide their level by 3 and then round down to get their effective spellcaster level.

Multiclassing Warlock with other casters

Note that Warlocks do not have the Spellcasting feature. They have Pact Magic. Pact Magic and Spellcasting are separate. The warlock spell slots are in addition to whatever spell slots you have from your effective caster level as described above. When you take a short rest, you only get your warlock spell slots back (not counting something like Wizard's Arcane Recovery feature). However the warlock spells slots are interchangeable with spell slots used to cast spells from other classes, or class abilities like divine smite.

Spellcasting abilities (Charisma, Intelligence, Wisdom)

Didn't I already bring this up in italics in the "Spellcasters" section? Yes. But it is so important that I'm going into it with more depth. If somebody shows you a high elf character with levels in Sorcerer X/ Druid Y, but don't see 2 reasons why this would possibly be a bad idea then you should keep reading. Any spells you learn from being a sorc use Charisma for determining the chance to hit, or the target's ability to resist the effects. Similarly, any spells you learn from being a Druid will use Wisdom for determining the chance to hit, or the target's ability to resist the effects. Multiclassing between these two classes is possible, but you have to be careful about it. This likely forces you to focus on one of these spellcasting stats (Wis or Cha) since BG3 will not let you roll for stats and get godlike ability scores. If you focus Wis, then you can choose whatever Druid spells you want, and just make sure you only pick Sorc spells that don't require dice rolls to hit or save, such as buffs like mirror image or jump. Vice versa if you pick Cha as your main casting stat, you will need to be careful about what Druid spells you pick.

I picked high elf for this hypothetical character, because as part of picking this race they get a cantrip that scales off Intelligence and a lot of people miss this detail, wondering why their high elf sorcerer is using Intelligence to cast ray of frost. Similarly, a drow's Faerie Fire scales off Charisma. Always look at what the casting stat is for a racial spell, and if it requires an attack roll or saving throw.

Making a spellsword or "gish" character

BG3 does not include the Hexblade subclass, which is overtuned at first level and has become a staple of "gish" builds. This is because the hexblade subclass allows you to use Charisma as both your spellcasting ability and your ability to determine accuracy and damage with weapon attacks. BG3 also does not seem to include the "SCAG" cantrips of booming blade or green flame blade. These spells help casters that don't have extra attack keep up in melee combat with martial characters that do have extra attack. It is a bit trickier to make gish characters without these options, but still doable. Single class options exist such as Eldritch Knight fighter, Arcane Trickster rogue, ranger, paladin, warlock (pact of the blade at level 3, thirsting blade at level 5), swords bard, and valour bard are viable options. But if you want to make a multiclassed gish, then you will want to get to extra attack as soon as you can. Ideally level 5, though level 6 is doable. If you are at level 7 and playing in melee without extra attack or the SCAG cantrips, you're going to have a bad time.

Multiclassing martials

Multiclassing martials is pretty simple, once you understand that extra attack from different classes do NOT stack. But similar to above with gish characters, you want to get to extra attack as fast as possible. You can afford to perhaps take a dip outside of your main class. But you absolutely want to have extra attack by the time you are level 7 as a martial character.

3rd Level Spells

Full caster classes learn 3rd level spells at Level 5. These spells are usually much stronger than the level 2 and below spells they had access to previously, so Level 5 is a big power bump for casters as well. Multiclassing as a full caster will delay the spell progression significantly and you may feel you are falling behind significantly when other characters are getting access to powerful 3rd level spells. So for similar reasons as with martials, you do not want to heavily multiclass prior to level 5.

Popular & Likely Viable BG3 Multiclass Builds

The below are common multiclass builds in D&D 5e which may work in BG3. I also added a couple builds that may work better in BG3 than they do in tabletop. These are by no means the only possible multiclass builds. There are tons and tons of them, and I myself am considering making my first character a paladin/rogue multiclass which I won't cover here since it isn't what folks would view as common or particularly synergistic.

Crit Fishing Half Orc - Barbarian 9/Champion Fighter 3

When a half-orc crits, they roll an extra damage die. When a 9th level barbarian crits, they roll an extra damage die. Champion fighters have double the crit chance (they crit on a 19 or 20 on the attack roll). And if a barbarian reckless attacks, you get advantage on the attack roll which further increases your odds of getting a crit (but also makes you a bit more vulnerable). If you want to go this route, make sure you use a two-handed weapon with a d12 damage die unless you find something extraordinary for your build. If you use something like a greatsword with a 2d6 damage die, then your extra damage dice from half-orc and barbarian would bring it up to 6d6 damage (average 21) on a crit. Whereas is you use a weapon like a battleaxe with a d12 damage die and crit then you will do 4d12 damage (average 26) on a crit. Weigh the opportunity cost.

Tanky Moon Druid - Moon Druid X/Barbarian Y

Moon druids can wild shape, and when they do they basically get a massive HP pool on top of their existing one. Barbarians can also rage, and while raged take only half damage from physical damage (the most common type). With Totem (a.k.a. Wildheart) of the Bear, then this rage damage resistance expands to instead half ALL damage except psychic. If using bear totem then I think the best split is Druid 9/Barbarian 3. But you could argue for other splits as well like Druid 10/Barbarian 2. One common point of confusion is that people think unarmored defense carries over into wild shape. Technically you only get the "natural armor" of your wild shaped form, and do not get any bonus to your AC from your barbarian unarmored defense. Some DMs let players use unarmored defense in place of the wildshpaed form's natural armor if unarmored defense is higher, but note that your dex and con change to that of the creature you are wildshaped into. Under no circumstance should unarmored defense stack with wildshaped natural armor. Weigh the opportunity cost.

Tanky Caster version 1 - Fighter X/Squishy Caster Y

The "squishy caster" in this scenario is usually a Wizard. It also works with lore bards, warlocks, and sorcerers, but these classes will often do a similar build where they choose paladin instead of fighter as will be discussed below. By taking your first level in fighter you get proficiency in (among other things) medium armor, shields, and constitution saving throws which is great for maintaining concentrations on spells. As well as a fighting style, and defense is a great option for this. Plus second wind for a bit of self-healing. By making your caster start as a fighter with 14 dex you'll have medium armor, a shield, and the defense fighting style for a total of 19 AC. Or you can put a few points into Strength to end up around 10-12 and wear heavy armor instead (assuming Larian keeps their rule of ignoring Strength requirement to wear heavy armor). This single level dip is enough to get from the fighter class for some people, but others will take a second level in fighter at some point (maybe character level 3) for Action Surge to allow them to have very burst damage heavy turns on occassion. Weigh the opportunity cost.

Tanky Caster version 2 - Cleric 1/Wizard 11

I guess this works on other squishy casters like sorcerer or bard or warlock, but I never hear people talk about doing this on anything but wizard. So I'll just specify wizard on this one. This build where you dip into Cleric is taken for similar reasons as the above Tanky Caster version 1 build; provide armor class to a squishy caster. The downsides are that you don't get the defense fighting style, second wind, or the option to get action surge. What you DO get is another level in a full caster class, which fighter does not provide. This benefit may increase the number and level of spell slots you have through the early and middle stages of the game. But 11th level and 12th level caster have the same number of spell slots so it does not make a difference near the end of the game. You also get the spells known from a cleric. This includes great spells that don't require you to make any attack rolls or force saves, such as guidance or bless. So having a very low Wisdom is fine as long as you are careful about what spells you prepare from your cleric side of things. And while healing word from the cleric does scale the healing slightly off of your Wisdom modifier, the amount healed is not really relevant when restoring a downed ally to life in the middle of combat. Lastly, you get the level 1 cleric subclass benefits. Many will pick a subclass that grants heavy armor proficiency such as life, nature, tempest, or war. I personally encourage knowledge domain to get expertise in two intelligence based skills that your wizard will already be great at. Weigh the opportunity cost.

Sorcadin - Paladin X/Sorcerer Y

This can be very similar to the above "Tanky Caster" where you get defensive features from Paladin, but are primarily a caster. But more commonly people play Sorcadin as a spellsword "gish" build. They get up close and smash things over the head, and they use all the extra spell slots they get from full caster levels in sorcerer to do divine smites and deal extra damage. Sorcerer is a popular pick because they get a lot of spell slots (as compared to warlock), and sorcery points to convert into more spell slots. Or they can use metamagic to cast powerful buff spells like haste as a bonus action. I personally feel that with a level 12 cap, it is ideal to start with Paladin 6 to get extra attack and the amazing paladin aura, then go the rest of the levels in sorc. Others may say to go 5 levels paladin and 7 in sorc to get access to 4th level sorc spells. Or may go 7 levels in paladin to get the improved paladin aura from your subclass, and 5 in sorc. You pick what you prefer. Larian gave white draconic bloodline sorc the spell Armor of Agathys as a spell known, so that is the sorc subclass I would pick with known info.

Note that Paladins get heavy armor proficiency only if that is your starting class. Caster focused Sorcadins who are mostly going sorc and only dipping into paladin for tankiness may want to opt for starting with 14 dexterity, starting as a sorc to get constitution saving throw proficiency, then take your level(s) in paladin. Though starting as a paladin and putting a few points in Strength instead of Dexterity is certainly valid. But Str based melee Sorcadins should likely start in Paladin, unless you are doing a more unique Dex sorcadin build. Weigh the opportunity cost.

Bardadin - Paladin X/Bard Y

This is very similar to the Sorcadin above, except bard instead of sorcerer. You can make a caster heavy focused baradin or a melee focused one, just like the sorcadin. However unlike Sorcadin, the bard has the valour and swords bard subclass. This means a melee focused Bardadin will focus on swords or valour bard for the first 6 levels to get extra attack and then 2 levels in paladin to unlock divine smite, and then the rest can go in bard. But starting as a bard and multiclassing into Paladin means you do not get heavy armor proficiency, so you'll want to be dex based if you go this route.

This build will do a similar amount of damage as the melee sorcadin since you don't have metamagic to make more spell slots, but you also have more spell slots available and at higher levels due to all your bard levels. Sorcadin probably wins on damage if you are using metamagic to quicken cast buff spells. But Paladin already has a ton of damage potential, and you are supplementing it with your bard spell slots so Bardadin damage is nothing to scoff at whatsoever. However you will be better at out-of-combat support through extra skill proficiencies, jack of all trades, and bardic inspiration than a sorcadin would be. I would play a bardadin over a sorcadin any day thanks to this utility. Weigh the opportunity cost.

Lockadin - Paladin X/Warlock Y

This is very similar to the Sorcadin above, except warlock instead of sorc. You can make a caster heavy focused lockadin or a melee focused one, just like the sorcadin. The melee focused lockadin takes advantage of getting the warlock's spell slots that come back on a short rest on top of their paladin slots. So they smite away, and then get back two of their spell slots back on a short rest. This multiclass is a lot more common with the warlock's hexblade subclass, but that is not present in BG3. So most that take this build would go paladin 5, then two in warlock, then paladin the rest of the way.

But now that Larian is changing Pact of the Blade to use Charisma on weapon attack and damage rolls, it becomes tempting to go at least 3 in warlock. And you want to do this right away so that you can start making weapon attacks with Charisma. This makes it tempting to go to 5 in warlock so that you can get extra attack. Finding break points on when to multiclass if you want to go this route is complex, and you may actually want to go Warlock 5 first and then Paladin 2, but then respec to Paladin 5/Warlock 3 when you hit level 8. From there put the rest of your levels in Paladin. Weigh the opportunity cost.

Bardlock - Warlock 2/Bard 10

One of Bard's greatest down sides is a lack of a good damage source. But they are Charisma casters, warlocks are charisma casters, warlocks get eldritch blast which is a decent damage cantrip, but made into a great damage cantrip with the warlock's agonizing blast eldritch invocation at second level. So the build usually goes taking 2 levels in warlock, the rest in bard.

But now that Larian is changing Pact of the Blade to use Cha on weapon attack and damage rolls, it becomes tempting to take 5 levels in warlock and then go into bard (likely lore subclass, but you can argue valour or swords) to make a spellsword character. Weigh the opportunity cost.

Sor-lock-bard-adain

Some combination of Paladin, Warlock, and the rest in either Bard or Sorc. Using the principles of above four builds. Maybe you make a paladin gish with the benefits of sorc and warlock spell slots. Maybe you make a bard-lock eldritch blast spammer, but dip into paladin for armor and shield proficiency. There are tons and tons of options between the 4 charisma casters. Weigh the opportunity cost.

The Ambush Ranger - Assassin Rogue X/Gloomstalker Ranger Y/Fighter Z

It is worth noting that Larian has already made several changes to the ranger class. And outside of this build, almost nobody plays the rogue's assassin subclass in tabletop D&D 5e so it may also be adjusted at release. But per tabletop, this build has a devastating opening turn of combat. Especially if it opens from stealth.

Gloomstalker gets bonuses that make them very difficult to detect in darkness by most creatures, helping them catch their enemy by "surprise."
Gloomstalker ranger gets to add their Wisdom bonus to their initiative rolls, helping them go early.
Assassin rogue gets advantage on any creature that has not gone yet in combat.
If you started the combat from stealth or otherwise caught the enemy off guard, then any character that is caught unawares during the first round of combat has the "surprised" condition. And assassin rogues automatically crit when they hit a surprised target
Gloomstalker rangers get to make one extra attack on the first turn, and if that hits then it does an extra 1d8 damage.
If you are dual wielding or using the crossbow expert feat or polearm master feat then you can make an additional attack using your bonus action.
Action surge, and get three more attacks.

Put all this together and you get 2 attacks from a level 5 ranger or fighter's attack action, another attack doing an additional 1d8 damage from gloom stalker, and a bonus action attack if you are properly equipped with equipment and possibly feats for a total of four attacks. Now add at least 2 levels of fighter to get action surge, which gives you another 3 attacks (2 from extra attack, 1 from gloomstalker opening round which does an additional d8 of damage) attacks for a total of 7 attacks on this absolutely absurd opening turn. One of the above attacks will also do sneak attack damage. Any of these attacks made against targets behind you in initiative will have advantage, and if the target is surprised then each of these attacks automatically crit which doubles the amount of damage dice rolled. And with all these possible crits, half-orc is looking awfully tempting for the extra weapon damage die for each attack that crits.

Once you get past the first round of combat, this build significantly quiets down. But after such a devastating opening, the enemy is usually down a few members. The exact level split may be up in the air, pending possible changes to assassin rogue and the ranger class. Weigh the opportunity cost.

This build does have a bit of an amusing "edgy powergamer reputation" in the tabletop community, but if playing singleplayer then there is nobody to judge you.

The "Life"berry Healer - Life Cleric X/Druid Y or Life Cleric X/Ranger Y

When a healing spell cast by a life cleric does healing, it does an additional 3 points of healing. The goodberry spell in tabletop summons 10 berries, each of which does 1 healing. And in tabletop the life cleric additonal healing does interact with each goodberry consumed. Meaning that a single cast of good berry will do provide 40 hitpoints of healing. But this spell has been changed in BG3 Early Access at least to instead summon four berries, each of which does 1d4 healing. On its own this change is a roughly equivalent amount of healing. But when BG3's goodberries interact with life cleric's additional healing bonus then this significantly cuts down the expected amount of healing to closer on the order of 19 hp. In BG3 Early Access this interaction will also only work if the life cleric who cast the goodberry spell is the one to consume the "life"berries, it does not work if another party member eats the "life"berries. It is still extremely powerful for a first level spell, but not as good as in tabletop. All you need is 1 level in life cleric, and the goodberry spell which can be obtained by 1 level in druid or 2 levels in ranger. You can make any of these three classes into your main class after that. Weigh the opportunity cost.

The Angry Rogue - Barbarian X/Rogue Y

For a rogue to get sneak attack they either need to have advantage on the attack roll, or the target must have another hostile (not counting the rogue) within 5 ft of it while the rogue does not have disadvantage. This is usually achievable, but not always. If only there was some way to just give yourself advantage... This is where two levels in barbarian comes in so you get Reckless Attack. You get advantage on your attack rolls, but enemies will have advantage on attack rolls against you for one round. Fortunately rage and uncanny dodge are there to help your defense a bit. The typical way to build this would be to go Strength based, as sneak attack only requires that you use a weapon with the finesse property, but not necessarily that you use dex on your attack rolls. So you can sneak attack by wielding a rapier for example with strength. And while you are at it, apply bonus rage damage if you are raging. If you go this strength route you will probably want to take your first level in barbarian, because that is the only way this build is getting medium armor proficiency (unless you pick the mountain dwarf as your race, or the moderately armored feat). That is how most tabletop players do this build, and I'd recommend doing 2 barb and 10 rogue to catch the bonus ASI/Feat that rogues get at level 10.

But in BG3 it may be possible to do this with a dex based build. Normally in 5e you do not get the extra barbarian rage damage to your attacks unless you use strength, and you cannot recklessly attack unless you use strength for the attack roll. BG3 Early Access does not impose either of these restrictions, and a Dex based barbarian is a good bit tankier while unarmored than a strength based barbarian is while unarmored. Plus a Dex based barb can start as a rogue and get the extra skill proficiencies that come with this.

Furthermore in BG3 you may want to take barbarian to level 3 and pick berserker subclass, and pick the thief subclass for rogue. This will give you two powerful bonus action attacks you can take as a barbarian/rogue multiclass when raging if these subclasses launch the way that they are in Early Access. Weigh the opportunity cost.

The Classic Eldritch Knight Gish - Eldritch Knight Fighter X/Abjuration Wizard Y

The fighter is great because it makes lots of attacks and gets lots of feats. The eldritch knight subclass adds a bit of magic on there. But the magic you can use is severely limited by both spell selection and number of spell slots, since eldritch knight is a 1/3 caster. This is where wizard comes in to shore up the eldritch knight's short comings, by adding more spells known and more spell slots. Abjuration wizard is great, since you'll likely be casting the shield spell a good bit with this build and each time you do you'll get a bit of temp HP thanks to abjuration wizard's Arcane Ward feature. I personally would go EK fighter 7 and abjuration wizard 5. Or EK fighter 8 and abjuration 4 if you prefer an extra ASI/Feat over third level wizard spells. Weigh the opportunity cost.

Absurd Lightning Damage - Tempest Cleric 2/Storm Sorc 10

Storm Sorcerer is typically viewed as one of the weaker subclasses in 5e, and many are hoping to see it buffed in BG3. However Larian has a homebrewed rule in BG3 Early Access that causes lightning damage to do double damage against targets which are "wet." And when a storm sorc casts a leveled spell that does lightning or thunder damage, then you can cause all enemies within 10 feet of you to take lightning or thunder damage equal to half of your Sorc level (cantrips don't trigger this effect). So if an enemy is wet (possible via a quicken cast of create water, an ally setting it up by throwing a water flask or other means, etc.) and you cast a lightning leveled spell like chromatic orb, you will do double damage with the lightning spell and damage to all nearby enemies equal to your sorc level. This is potentially very powerful without multiclassing.

But wait, there's more. Tempest domain clerics get channel divinity at second level allowing them to roll max damage on all the damage on a lightning or thunder spell once a short rest (essentially double damage). So by combining this with storm sorc and the BG3 EA wet condition making enemies vulnerable to lightning damage, this means that once a short rest you can do 4x damage with a lightning spell on a wet enemy, and simultaneously deal damage equal to your sorc level on all enemies near you. And you can use metamagic to do even more damage by enhancing it or twin casting the spell if action economy allows. This is a gimmicky but viable build in tabletop, and if Larian's homebrewed "wet = double lightning damage" stays in then it will be even more gimmicky but also more viable in BG3. I recommend first level sorc to get constitution saving throw proficiency, then two cleric, then the rest sorc. You do not need to have a high Wisdom for this build, Cha is your main casting stat. Just make sure that the cleric spells you pick are ones that don't require an attack roll or save. Weigh the opportunity cost.

Sorlock - Warlock X/Sorcerer Y

Note it is almost certain that the once mighty tabletop build referred to as the "coffeelock" where you get infinite spell slots will NOT work in BG3. But even ignoring this rulebending build, Sorlocks are still viable. Typically the premise is that sorcerers can do great burst damage. Wouldn't it be nice if they can do some extra consistent damage on top of that? So start sorc, take a two level dip in warlock for eldritch blast and agonizing blast eldritch invocation, then go sorc the rest of the way. This also gives you some extra warlock pact magic spell slots which come back on a short rest so you can convert into sorcery points to fuel your metamagic shenanigans. Cast a powerful eldritch blast with your action, and follow it up with a quickened fireball with your bonus action or quickened haste to buff your paladin who needs to go charging into combat.

But now that Larian is changing Pact of the Blade to use Charisma on weapon attack and damage rolls, it becomes tempting to take 5 levels in warlock and then go into sorc to make a spellsword character. Weigh the opportunity cost.

A note on Monk

The best monk features often rely on Ki points, which you can only get more of by taking more levels in Monk. If you want to multiclass out of monk, most find that the opportunity costs are too high and you would have been better off just staying with monk. Taking a dip into monk grants you melee combat focused features that only work if you are unarmored, so will be useless on most characters. The monk's unarmored defense does not stack or otherwise interact with unarmored defense from a wildshaped druid, or a barbarian's unarmored defense. These reasons are some of the more prominent ones for why monk multiclasses are not common in tabletop. Larian has said they are making changes to monks in BG3. Depending on these changes, monk may become a more tempting multiclass target

Some entertaining monk rogue multiclass options include Monk 10/Spore Druid 2. Or Shadow Monk 10/warlock 2 so that you can cast darkness on yourself and enemies blinding them, but not blinding yourself thanks to devil's sight eldritch invocation which allows you to attack with advantage. Until we know what changes Larian makes to monk, it is difficult to recommend any Monk builds.

A note on Thief Rogue

The thief rogue's Early Access ability Fast Hands allowing them to take two bonus actions each round may be the most power shifting feature in BG3. Many martial characters will get benefit from dual wielding, crossbow expert, or polearm master with a 3 level dip in thief rogue. This is especially the case for ranger, which is notoriously starved for bonus actions. Bonus action controllable spells like spiritual weapon or flaming sphere just got their damage doubled by this. Currently in BG3 early access, Larian does not restrict you from casting a leveled spell with your action and bonus action. This means that a Thief Rogue 3/Fighter 2/Sorc 7 would be able to cast a spell with their action, action surge and get another action to cast a leveled spell, use metamagic to cast a powerful spell as a bonus action, and use metamagic to cast another powerful spell with your extra bonus action. You will burn everything you have to do this, and you will be limited to 4th level spells, so maybe that will balance things. A raging berserker barbarian now gets two very powerful bonus action attacks when they rage, which could go great with the Angry Rogue build. But if thief rogue is going to launch as it is in early access, you should always ask yourself, "Is 3 levels in thief rogue worth the opprotunity cost."