Booming Safeguard

You touch a willing creature, granting it Temporary Hit Points equal to 2d6 plus your spellcasting ability modifier.

When damage reduces the last of the Temporary Hit Points granted by this spell to 0, the spell ends with a thunderous detonation. Each other creature of your choice in a 5-foot Emanation originating from the target must make a Constitution saving throw. On a failed save, a creature takes 2d6 Thunder damage and is pushed 10 feet away from the target. On a successful save, the creature takes no damage and isn’t pushed.

Using a Higher-Level Spell Slot. The Temporary Hit Points and Thunder damage each increase by 1d6 for every spell slot level above 2.