The Great Shell

With a silent prayer to the Great Turtle you are protected by the essence of the Great Shell. You gain 20 Temporary Hit points and your Armor Class is increased by +3 for as long as the temporary Hit Points last. These bonuses last until the temporary Hit Points are destroyed through taking damage or lost due to taking a Long rest.

When the spell is ended due to taking damage rather than a long rest the essence of the Great Shell explodes with Radiant light in a 20 foot emanation. Allies in the area of effect are healed for 2d6 Hit Points, and enemies in the area take 2d6 Radiant damage.