Dia

You cause a burst of holy energy to manifest next to a creature.

The creature makes a DEX saving throw | Fail: It takes 1d4 HOLY damage and becomes marked until the end of your next turn. While marked, it glows, yielding dim light in a 2m radius. If the creature takes any damage before this effect ends, the mark is consumed and it takes an extra 1d8 HOLY damage.

This spell's follow-up damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8)

A very, very small holy hand grenade.