Deathbane Hex

You place a curse on an undead creature that you can see within range. Until the spell ends, you deal an extra 1d6 Radiant or Psychic damage (Caster's choice) to the targeted undead whenever you hit it with an attack roll. The target has Disadvantage on Wisdom checks and Saves. This spell allows an Undying Warlock to attack the single undead targeted without negating the caster's Among the Dead ability for that creature. Furthermore, a successful save against the caster's Among the Dead DC must be made each time the Deathbane Hex targeted undead wishes to attack the Undying Warlock.

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

Using a Higher-Level Spell Slot. Your Concentration can last longer with a spell slot of level 5 (up to 8 hours).