Armor of Agathys 1st level abjuration

Casting Time: 1 action

Range: Self

Components: V, S, M (a cup of water)

Duration: 1 hour

Tags: warlock level1 abjuration

A protective magical force surrounds you, manifesting as a spectral frost that covers you and your gear. You gain 5 temporary hit points for the duration. If a creature hits you with a melee attack while you have these hit points, the creature takes 5 cold damage.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, both the temporary hit points and the cold damage increase by 5 for each slot level above 1st.

You can find more information on this spell in: PHB.215