Master Refrum

As a bonus action, Refrum can expend a spell slot to cause its melee weapon attacks to magically deal an extra 10 (3d6) radiant damage to a target on a hit. This benefit lasts until the end of the turn. If the priest expends a spell slot of 2nd level or higher, the extra damage increases by 1d6 for each level above 1st.

Refrum is a 5th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 13, +5 to hit with spell attacks). The priest has the following cleric spells prepared:

Cantrips (at will): light, sacred flame, thaumaturgy

Level 1 (4 slots): cure wounds, guiding bolt, sanctuary

Level 2 (3 slots): lesser restoration, spiritual weapon

Level 3 (2 slots): dispel magic, spirit guardians

Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: 3 (1d6) bludgeoning damage.