Create sentient undead

As an action in combat: you reach out with the onyx and the heart, letting the blood flow onto the gem, and touch the gem to the corpse’s head. The corpse rises as a death knight, vampire(cr17 or lower), or mummy lord of your choice keeping any weapons and armor they had and any proficiencies pertaining to them. The undead assumes the stats of the monster in the DMG, and is sentient but subservient to the caster. If cast in combat the undead stays animated for 24 hours, after which the corpse will turn to ash and cannot be reanimated or revived without a true resurrection or a wish spell.

As a ritual casting(24 hour casting time): when you cast this pell as a ritual you may choose to raise several more types of undead, and they are bound until they are destroyed but can also attempt to defy their masters orders by making a DC 26 Wisdom saving throw, at disadvantage if the order was given to them directly and in person, so long as they believe their course of action to be better or not overtly harmful. Magic casters only know any spells they knew in life, and gain a maximum of 2 legendary actions and one resistance. 

the types of undead include: 

Demilich- requires a small phylactery worth 10,000 prepared and the body of a powerful magic caster (18th level or cr18). The caster rolls a D100 and on a roll of a 3 or lower the spell fails, the targeted corpse is disintegrated (requiring a wish spell to revive and recover its soul), and the phylactery shatters becoming worthless.

Nightwalker- requires two heroic beings that have achieved great heights(combined level or CR of at least 28) and a chunk of stone from the shadow fell that has been imbued with the energies of the plane inserted into the hearts of each corpse. The caster rolls a D100, on a roll of a 6 or lower the spell fails and the bodies turn to ash along with the stones.

Lich- the target of the spell must be a magic caster must have achieved ninth level spell slots, a combined level of 20 pure caster classes, and has learned at least one ninth level spell. This ritual take 48 hours, requires a phylactery worth at least 50,000 gold coins made by a master craftsman, and requires the entity casting to roll a D100. On a 10 or lower the ritual fails, the targeted corpse is disintegrated, requiring a wish spell to reform the soul of the entity, and the phylactery is shattered becoming worthless.

You may have no more than 5 entities controlled with this spell at any one time, any attempt to do so will destroy the oldest creature permanently.

Any spell caster who is raised by this spell and knew it loses the ability to cast it, instead gaining a different 9th level spell of its choice.