Aqua Shell

A protective sphere of swirling water surrounds the target. For the duration, it gains 5 temporary hit points at the start of each of its turns. While it has any amount of these temporary hit points, weapon attack rolls against it have disadvantage and it has resistance against fire damage.

Using a Higher-Level Spell Slot. The spell lasts up to 10 minutes and provides 10 temporary hit points at the start of the target's turns, if cast with a level 5+ spell slot.