Glyph of Warding: Sleep is a level 3 abjuration spell. This spell is a variant of the Level 3 Abjuration Spell, Glyph of Warding. This variant of the spell allows spellcasters to inscribe a ward that can put enemies to Sleep when triggered.
Description
The glyph emits a soothing magic that puts everyone within range to Sleep when stepped on by an enemy. Any creatures within the area of effect (that aren't immune to magical sleep) that fail the Dexteritysaving throw will be put to Sleep.
The glyph will last until triggered, or until a Long Rest.
Attack rolls against it have Advantage, and any attack that hits the creature is a critical hit if the attacker is within 1.5 m / 5 ft of the creature.
Removed by taking damage, getting wet, receiving Help or being Shoved.
Only those considered an enemy can trigger the glyph. For the player's party this is indicated via a red circle beneath the creature, red outlines when highlighted, and denoted by a red dot on the minimap. Neutral, friendly, and allied creatures (highlighted yellow/green/blue respectively) can safely go through the glyph.
This makes using the glyph as a trap difficult for many encounters. Specifically, those that normally only consider creatures hostile after dialogue.
When the glyph is triggered, everyone within the area is affected, regardless of allegiance.
When the spellcaster is surrounded by enemies, sometimes it is worth throwing the glyph down right at their feet. This is true for most AOE spells but it is especially so for the sleep variant of Glyph of Warding:
The shared Initiative system means an ally can immediately shove/help the spellcaster awake should they fall asleep due to their own glyph.