Anubis

Aura of Death. Any creature that makes a melee attack or starts its turn within five feet of Anubis must make a DC 15 Constitution saving throw or take 20 (4d10) necrotic damage.

Deadly Fortitude. When Anubis is reduced to 0 hit points, he can choose to be reduced 20 instead. Every time he is reduced to 0 hit points after that, he must make a save to be reduced to 20 instead with a DC of 10 + the excess damage he took. 

Spellcasting. Anubis is a 20th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 21, +13 to hit with spell attacks). Anubis has following sorcerer spells prepared:
Cantrips (at will): Blade Ward, Chill Touch, Fire Bolt, Green-Flame Blade, Infestation, Thunderclap
1st level (4 slots): Chaos Bolt, False Life, Magic Missile, Witch Bolt
2nd level (3 slots): Blindness/Deafness, Cloud of Daggers, Shadow Blade
3rd level (3 slots): Counterspell, Enemies Abound, Melf's Minute Meteors
4th level (3 slots): Blight, Sickening Radiance, Vitriolic Sphere
5th level (3 slots): Cloudkill, Enervation, Synaptic Static
6th level (2 slots): Circle of Death, Disintegrate
7th level (2 slots): Finger of Death, Crown of Stars
8th level (1 slot): Abi-Dalzim's Horrid Wilting
9th level (1 slot): Psychic Scream

Multiattack. Anubis makes five melee attacks or two Staff attacks, one Touch of Death attacks and one Tried and Found Wanting attack. 

Touch of Death. Anubis reaches out and touches a creature within five feet of him. The creature makes a DC 20 Constitution save, taking 48 (12d8) necrotic damage on a failed save and half as much on a successful save.

Tried and Found Wanting. Anubis summons the golden scales and weighs a projection of a target's soul against the feather. The target makes a DC 30 Charisma saving throw, taking 100 (20d10) necrotic damage on a failed save or healing for 20d10 on a successful save.

Anubis' Staff. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit: 40 (4d12 + 16) bludgeoning damage plus 18 (3d12) necrotic damage. 

Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit: 36 (5d8 + 16) piercing damage plus 18 (3d12) necrotic damage . 

Claw. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit: 36 (10d4 + 16) slashing damage plus 18 (3d12) necrotic damage.