Delirium

You cause a creature within range to experience delirious thoughts. Until the spell ends, you deal an extra 1d6 Psychic damage to the target whenever you hit it with an attack roll. Also, hallucinations cause the creature to always be considered within 5 feet of an ally for the purposes of Sneak Attack. 

If the target drops to 0 Hit Points before this spell ends, you can take a Bonus Action on a later turn to turn a new creature delirious.

Using a Higher-Level Spell Slot. Your Concentration can last longer with a spell slot of level 2 (up to 4 hours), 3–4 (up to 8 hours), or 5+ (24 hours).