Dark Arbiter

You empower a number allies equal to or less than your spellcasting ability modifier who are within 60-ft of you and within line of sight, granting them Dark Arbiter for 2 rounds.

Once per round for the duration of the spell, those effected deal an additional 1d4 necrotic damage to their target on successful melee, ranged, and spell attacks which require an attack roll, granting temporary hit points equal to the Necrotic damage done by Dark Arbiter. Temporary hit points gained through this ability last for 1 hour, after which they are absorbed as healing. 

At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d4 for each slot level above 3rd.