The Deadsbane Helm(Cursed)

Wielder has immunity to necrotic damage, and
deals 1d8 extra radiant damage on attacks against
undead or lycanthropes. Additionally, they heal
1d8 hit points upon defeating an undead creature.
Cursed - The Helm naturally attracts undead to its location, and can also drive the wielder to fanatical bouts of undead hunting. Anyone wearing the
Helm who tries to remove it takes 2d8 radiant
damage unless they are a paladin, and must
succeed on a Strength check 13 to remove it
successfully.