Azreal

Coated in Darkness. Azreal's attacks are magical and any weapons she uses becomes coated with the darkness of The End. When she hits with any weapon, the weapon deals an extra 6d8 force damage (included in the attack). 

Innate Spellcasting. Azreal's spellcasting ability is Intelligence (spell save DC 25). It can innately cast the following spells, requiring no components(i.e cannot be counterspelled):

At will: detect evil and good, invisibility (self only)

3/day each: darkness, dispel evil and good, pulse wave

2/day each:gravity fissure,disintegrate,resurrection,commune

1/day each:  maddening darkness,dark star,Ravenous Void

Resolution. Each spell in Azreal's spell list can be casted once more however the damage die is reduced by 2. E.g 2d8 becomes 2d6.  

Shadows of The End.  Once per day, Azreal can create up to a total of 4 shadow clones of herself each clone gains health equal to the number of clones +1 divide by her current health. In addition all of her clones stats are reduced by the number of clones *2. In addition her clones only keep her spell list, her attacks and coated in Darkness.(Rules that may be added if more challenge is wanted) Everytime a clone is defeated it blosters the other clones and the gain stats as if  there were only the remaining number of clones present(e.g when 1 of 4 is defeated then the other 3 gain stats as if only 3 clones had been summoned) and the heals each 20 hit points.

Legendary Resistance (4/Day). If Azreal fails a saving throw, she can choose to succeed instead.

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

Multiattack. Azreal makes three attack with NightBringer or two Crescent Slash.

Nightbringer. Melee Weapon Attack: +18 to hit, reach 5 ft., one target. Hit: 23 (3d10 + 10) slashing damage plus 27 (6d8) force damage.

Crescent Darkness. Ranged Weapon Attack: +18 to hit, range 150/600 ft., one target. Hit: 17 (2d10 + 10) piercing damage plus 27 (6d8) force damage.

Cloak of The End. As a bonus action , once per day Azreal can coat herself in the darkness of The End. She gains the following benefits for 1 minute:

+3 to her AC

Resistance to everything except pyschic

Consuming Darkness. As a reaction she can reduce the damage of an incoming attack  of any damage type excluding psychic by half

Feast of Darkness.  As a part of Consuming Darkness Azreal can make a contested Wisdom check. If she's suceeds this check, the half of the damage which goes through heals her instead.

Consuming Darkness. As a reaction she can reduce the damage of an incoming attack of any damage type excluding psychic by half

Feast of Darkness.  As a part of Consuming Darkness Azreal can make a contested Wisdom check. If she's suceeds this check, the half of the damage which goes through heals her instead.

Azreal 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. Azreal regains spent legendary actions at the start of its turn.

Shadow Step. Azreal, when in dim light or darkness, can magically teleport, along with any equipment she is wearing or carrying, up to 120 feet to an unoccupied space she can see that is in dimlight or darkness.

Scything Darkness(Costs 2 Actions). Azreal emits darkness of Resolution outward. Each creature of her choice in a 10-foot radius must make a DC 25 Dexterity saving throw, taking 14 (4d6) slashing damage plus 14 (4d6) force damage on a failed save, or half as much damage on a successful one.

The End(Costs 3 Actions). The Azreal targets one creature it can see within 30 feet of her. If the target is a creature that has 100 hit points or fewer.