Undead Servant. The raven is considered an undead servant which follows every command even if it means death. You can communicate with a special language with it that only you and the raven share. the raven will follow any instruction until it succeeds, dies or you call it back. The raven can only hear you in a range of 120 ft.

Reborn From Bones. Should the undead raven die, it will completely fade from existence and lives on in the Shadow Realm. To summon it you need to perform a ritual and have the correct components at hand. You need bones of a small or tiny mammal and 2 gems (worth at least 50 gp each). If you only use 1 gem the raven will come back, missing an eye. He will have disadvantage on Perception checks based on sight, all saving throws and attacks against it will have advantage. The ritual takes 1 hour to perform.

The undead raven does not need to breathe, eat, drink or sleep.

Shared Vision. You can always perceive every sense trough the raven. Your and his eyes will turn a pale white. You can no longer see for yourself until you end Shared Vision or if the raven is more than 1 mile away from your location or on another plane of existence.

Unholy Sacrifice. You can command the raven to fly towards an enemy where he will impale the enemy and sacrifice himself in a necrotic explosion. The raven will inflict [roll]3d10+6[/roll] necrotic damage to the enemy and die itself.