Astral stalker

Stalkers quarry. The astral stalker as a bonus action may mark a creature it can see within 120ft and for the next 24 hours will knows its location even if its on another plane and has advantage on (intelligence) investigation checks related to that target. 

Naturally invisible. The astral stalker is under the effects of greater invisibility until it makes an attack.

Stalkers advantage. If the astral stalker has advantage it deals an additional  4d6 damage on its attacks it has advantage with. 

Legendary Resistance (2/Day). If the astral stalker fails a saving throw, it can choose to succeed instead.

Multiattack The astral stalker makes three attacks: which can be any combination of its claws and throat dart 

Claws.Melee Weapon Attack: +9 to hit, reach 5 ft., 1 target. Hit: 18 (4d6 + 6) [slashing] damage. 

Throat dart. RangedWeapon Attack: +13 to hit, range 60/120 ft., 1 target. Hit: 18 (5d4 + 8) [poison] damage. if this hits the target must make a dc 20 constitution save or be paralyzed for 1 minute and on a successful save they are poisoned instead. at the eat of the targets turn they are aloud to retry the save to cure either fully. 

The astral stalker can take 1 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. The astral stalker regains spent legendary actions at the start of her turn.

Attack (Costs 1 Actions). The astral stalker makes a claw attack on a creature within range.

Turn invisible (Costs 1 Actions). The astral stalker goes back under the effects of greater invisibility (see Naturally invisible).