This and other magic items I've created are collected together in the attached PDF.
Unholy Ring of Skeletal Mastery: This ring was crafted by a powerful necromancer with questionable romantic interests. Although it looks as if it's formed from bone, it's always cold to the touch and, as far as anyone can tell, unbreakable. +3 bonus to any checks involving the undead, and once a day when battling any undead creature of your level or below, force it to make its basic attack against a target of your choice as a quick action, even if it must move to do so. The move will not provoke opportunity attacks. If the creature is a skeleton, the attack does full damage. If it is any other type of undead monster, the attack only does half damage.
Quirk: Extra Creepy. No matter how attractive you may find someone, you're pretty sure they'd be more so with pale skin, blue lips and a lower body temperature.