Barkskin

From Player's Handbook, page 217.

Description
2nd-level transmutation


 * 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.

Learned By

 * Classes: Druid, Ranger
 * Subclasses: Cleric (Nature Domain), Druid (Circle of the Land (Forest))