Amulet of Undead Sanctuary

Immunity to necrotic damage

Undeads will not attack you

Undead Fortitude. If damage reduces the character to 0 hit points, they must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the character drops to 1 hit point instead.

Vulnerable to holy damage