Devil’s Sight. Magical darkness doesn’t impede Zariel’s darkvision.

Radiant Hellfire Weapons. Zariel’s weapon attacks are magical. When she hits with any weapon, the weapon deals an extra 36 (8d8) raidiant damage (included in the weapon attacks below).

Innate Spellcasting. Zariel’s innate spellcasting ability is Charisma (spell save DC 26). She can innately cast the following spells, requiring no material components:

At will: alter self (can become Large when changing her appearance), detect evil and good, fireball, invisibility (self only), wall of fire

3/day each: blade barrier, dispel evil and good, finger of death

Legendary Resistance (3/Day). If Zariel fails a saving throw, she can choose to succeed instead.

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

Regeneration. Zariel regains 20 hit points at the start of her turn. If she takes radiant damage, this trait doesn’t function at the start of her next turn. Zariel dies only if she starts her turn with 0 hit points and doesn’t regenerate.

Special Equipment. Zariel wields a modified Sword of Zariel that's bonus damage is necrotic instead of radiant and a  modified Vorpal Greatsword that can choose the limb that is lobbed off instead of it always being the head. 

Strong Armed. Zariel posses overwhelming strength and  power that allows her to wield two handed weapons while only using one hand and versatile weapons with are always treated as being wielded in two hands even if she is only holding it in one. Weapons also deal twice their damage dice when she wields them  (included in the weapon attacks below).

Multiattack. Zariel attacks twice with her Vorpal Greatsword and once with Sword of Zariel. She can substitute Horrid Touch for Sword of Zariel.

 Vorpal Greatsword. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 26 (4d6 + 12) piercing damage plus 36 (8d8) radiant damage.
When the Zariel rolls a 20 on an attack roll, the target is decapitated or one of their limbs is severed from their body. (At your option, the attack can instead deal an extra (6d8) slashing damage when not decapitating.) A target is immune to this effect if it is immune to slashing damage, has legendary actions and is immune to decapitation if it doesn’t have or need a head, or if you decide that the target is too large for its head to be cut off by Zariel's greatsword.

Sword of Zariel. Melee Weapon Attack: +16 to hit, reach 5 ft., one target. Hit: 21 (2d8 + 12) slashing damage, or 23 (2d10 + 12) slashing damage when used with two hands, plus 36 (8d8) raidiant damage and 17 (3d10) necrotic damage. A creature that takes this radiant or necrotic damage must succeed on a DC 21 Constitution saving throw or be blinded until the end of its next turn.

Horrid Touch (Recharge 5–6). Zariel touches one creature within 10 feet of her. The target must succeed on a DC 26 Constitution saving throw or take 44 (8d10) necrotic damage and be poisoned for 1 minute. While poisoned in this way, the target is also blinded and deafened. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

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

Zariel can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. Zariel regains spent legendary actions at the start of her turn.

Attack. Zariel makes one attack with either her Vorpal Greatsword or with the Sword of Zariel 

Immolating Gaze (Costs 2 Actions). Zariel turns her magical gaze toward one creature she can see within 120 feet of her and commands it to combust. The target must succeed on a DC 26 Wisdom saving throw or take 22 (4d10) fire damage.

Teleport. Zariel uses her Teleport action.