Champion of Tharizdun (Necrotic)

Death Throes. When the Champion dies, it explodes, and each creature within 30 feet of it must make a DC 20 Dexterity saving throw, taking 70 (20d6) necrotic damage on a failed save, or half as much damage on a successful one. The explosion corrodes any non-magical objects in that area that aren't being worn or carried, and it destroys the Champion's weapons.

Deathly Aura. At the start of each of the Champion's turns, each creature within 5 feet of it takes 10 (3d6) necrotic damage, and non-magical objects in the aura that aren't being worn or carried corrode. A creature that touches the Champion or hits it with a melee attack while within 5 feet of it takes 10 (3d6) necrotic damage.

Magic Resistance. The Champion has advantage on saving throws against spells and other magical effects.

Magic Weapons. The Champion's weapon attacks are magical.

Multiattack. The Champion makes two attacks: two with its longswords and two with its daggers.

Longsword. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 21 (3d8 + 8) slashing damage plus 13 (3d8) necrotic damage. If the Champion scores a critical hit, it rolls damage dice three times, instead of twice.

Dagger. Melee Weapon Attack: +14 to hit, reach 30 ft., one target. Hit: 15 (2d6 + 8) slashing damage plus 10 (3d6) necrotic damage.

Teleport. The Champion magically teleports, along with any equipment it is wearing or carrying, up to 120 feet to an unoccupied space it can see.

Dash - The Champion can use 1 legendary action to move half it's movement, without prompting opportunity attacks.

Longsword Attacks - The Champion can use 1 legendary action to make 2 attacks with it's longswords.

Fiery Wrath - The Champion can use 2 legendary actions to make all shadows in a 20ft radius, centered on the Champion, lash out like inky whips. All creature in range must make a DC 20 Dexterity saving throw or take 3d8 necrotic damage and be restrained for 1 turn, on a save damage is halved and are not restrained.

Feeding the Fire - The Champion can use 3 legendary actions to make all attacks deal an extra 1d8 necrotic damage and heal as much damage as they deal for 1 turn.