Skull

Even - The character must defeat a powerful undead creature alone. Odd - You summon an avatar of death-a ghostly humanoid Skeleton clad in a tattered black robe and carrying a spectral scythe. It appears in a space of the DM's choice within 10 feet of you and attacks you, warning all others that you must win the battle alone. The avatar fights until you die or it drops to 0 Hit Points, whereupon it disappears. If anyone tries to help you, the helper summons its own avatar of death. A creature slain by an avatar of death can't be restored to life.