March of the Dead (5e Equipment)
From D&D Wiki
Weapon (longsword), legendary (requires attunement)
March of the Dead is a longsword with three skulls carved along the flat of the blade. You can choose up to three creatures with a CR up to your proficiency bonus, that you kill while using this weapon to become bound to it, these creatures can then be summoned or dismissed as an action. Summoned creatures appear at a point selected by the sword's bearer, up to 20 feet away. You must choose to bind a creatures as soon as they are killed. These creatures are friendly to you and your companions and will obey telepathic commands. If you issue no commands, the creature will defend itself but take no other actions.
Once bound to the sword, creatures becomes the creature type undead and gain undead fortitude Creatures that are already undead cannot be bound to march of the dead. A creature cannot be unbound from the sword unless it is released by the sword's owner or destroyed/reduced to 0 hit points. Creatures bound to the sword retain class, levels, abilities, features, and traits, as well as memories and personality traits from their life and may act "normally," unless doing so contradicts orders from the sword's owner.
A creature summoned from the sword remains under the owner's control for a period of six hours, after which point they are automatically dismissed and cannot be summoned again for 24 hours. This wait period decreases by four hours for each hour less that you have the creature under your control.
You gain +3 to attack and damage rolls with this magic weapon, this bonus decreases by 1 for each creature currently being controlled.