Tomb of Levistus

As a reaction when you take damage, you can entomb yourself in ice, which melts away at the end of your next turn. You gain 10 temporary hit points per current level, which take as much of the triggering damage as possible.

Immediately after you take the damage, you gain vulnerability to fire damage, your speed is reduced to 0, and you are incapacitated. These effects end when the ice melts.