Costine The Shadowstalker

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

Assassinate. During her first turn, Costine has advantage on attack rolls against any creature that hasn't taken a turn. Any hit she scores against a surprised creature is a critical hit.

Sneak Attack. Once per turn, Costine deals an extra 14 (4d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of costine that isn't incapacitated and she doesn't have disadvantage on the attack roll.

Fey Ancestry. Costine has advantage on saving throws against being Charmed, and magic can’t put her to sleep.

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

Soul Thirst. When she reduces a creature to 0 hit points, Costine can gain Hit points equal to half the creature’s hit point maximum.

Evasion. When Costine is subjected to an effect that allows her to make a DEX saving throw to take only half damage, she instead takes no damage if she succeeds on the saving throw, and only half damage if you fail.

Spellcasting. Costine can cast spells. Her spellcasting ability is wisdom (spell save DC 20, +12 to hit with spell attacks). She has the following spells prepared:

cantrips (at will): vicious mockery, thorn whip eldritch blast (3 blasts)

1st level (5 slots): Hunters mark, find familiar, 

2nd level (4 slots): Misty step, silence, skywrite, darkness, alter self

3rd level (4 slots): flame arrows, conjure animals (The animals are considered undead)

Multiattack. Costine makes three attacks.

Shortsword. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 6 (2d6 + 3) piercing damage, and the target must make a DC 16 Constitution saving throw, taking 24 (5d6) poison damage on a failed save, or half as much damage on a successful one.

Shortbow. Ranged Weapon Attack: +10 to hit, range 80/320 ft., one target. Hit: 7 (2d8 + 3) piercing damage, and the target must make a DC 16 Constitution saving throw, taking 24 (3d6) necrotic on a failed save, or half as much damage on a successful one.

Costine 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. She regains spent legendary actions at the start of her turn.

Shadowstalker (Costs 1 action): Costine seamlessly blends into the shadows, becoming invisible until her next attack. During this time, she gains 15 movement speed if not already on her turn and she can move without provoking opportunity attacks.

No shot (Costs 1 action): Upon seeing an arrow or cantrip flying towards her, Costine instead redirects it away from her and back to the attacker, reusing the to hit and damage.

Necrotic Arrow (costs 1 action): Costine fires an arrow imbued with necrotic energy at a target within 100 Ft. The target must make a dc 18 Dexterity saving throw or take 4d6 necrotic damage.

Shadow bind (costs 2 actions): Costine uses dark magic to ensnare a creature within 30 feet with shadowy tendrils. The target must make a Strength saving throw or be restrained until the end of its next turn.

Shadowstep (Costs 2 actions): Costine melds into the shadows, disappearing from view and reappearing in a different location within 60 feet. 

Abyssal Shot (Costs 3 Actions):  Costine fires a potent arrow infused with the essence of the Abyss. The arrow creates a dark rift upon impact within a 20 ft sphere that takes away 10 ft of movement from creatures within the range as well as dealing 6d6 necrotic damage on impact to creatures in the sphere. Any creature who starts their turn in this sphere must succeed on a dc 17 wisdom saving throw or they get 4d6 psychic damage dealt to them.