Barkskin

2nd-Level Transmutation Spell

Source: Player's Handbook

Spell Lists: Druid Spells, Ranger Spell List

Casting Time: 1 action

Range: Touch

Components: V, S, M (a handful of oak bark)

Duration: Concentration, up to 1 hour

You touch a willing creature. Until the spell ends, the target’s skin has a rough, bark-like appearance, and the target’s AC can’t be less than 16, regardless of what kind of armor it is wearing.