Armour Class

Template:Up to date  Armour Class (AC) is a measurement of how difficult a creature is to be hit by an attack. AC can be increased by equipping Armour and Shields, by selecting certain Feats when leveling up, or utilizing certain Magic Spells.

The formula that determines AC is:

Armour Class = Base Armour Class + Dexterity Modifier + Other Bonuses and Penalties

• Base Armour Class is the number seen in shields in the descriptions of armour. When unarmoured, a creature naturally has a Base AC of 10.
  • Mage Armour sets the base armour class to 13 if the target isn't wearing any armour
• The AC bonus from Dexterity Modifier may be capped when wearing heavier types of Armour.
  • Light Armour doesn't cap the Dexterity AC. Clothing doesn't either, but they don't count as armour at all.
  • Medium Armour typically caps the Dexterity Modifier to +2 , although there are some armours with an "Exotic Material" trait that allow the wearer to get the full Dexterity bonus to AC. For example, Yuan-Ti Scale Mail, Sharpened Snare Cuirass, or Armour of Agility.
  • Heavy Armour ignores any bonus (or penalty) from the wearer's Dexterity.

• The final term, "Other Bonuses and Penalties" is a very valuable source of AC, it is subject to the least amount of restrictions, but are also relatively rare
  • Barbarian and Monk have access to the Unarmoured Defence feature. Allowing them to add their Constitution Modifier and Wisdom Modifier to AC respectively.
  • Certain Clothing and Armours grants bonus AC outside of their Base AC. Potent Robe is an example of this.
  • A few spells grants bonus AC: Shield of Faith, Shield, Mirror Image, and Haste. But all of these either don't last long, or requires concentration.
  • Spells that decreases AC is even rarer: Slow can do this directly, but is subject to a saving throw; Chromatic Orb: Acid and Melf's Acid Arrow can achieve this via an Acid Surface, but can be swiftly negated when the victim leaves the surface.

In order to successfully hit a creature, the Attack Roll must have a number equal to or greater than the target's Armour Class. This means, typically, each point of AC makes a creature 5% harder to hit.