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Casting Time: 1 action
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.
You can find more information on this spell in: PHB.217