Legendary Resistance (1/Day).

If the slasher fails a saving throw, it can choose to succeed instead.

Shrouded Presence.

The slasher is immune to any effect that would sense its emotions or read its thoughts, and it can't be detected by abilities that sense Fiends.

Actions

Multiattack.

The slasher makes two Slasher's Knife attacks.

Slasher's Knife.

Melee or Ranged Weapon Attack: +7 to hit, reach 5 ft. or range 30/60 ft., one target. Hit: 6 (1d4 + 4) slashing damage plus 21 (6d6) necrotic damage. If the target is a creature, it suffers a lingering wound that causes it to take 7 (2d6) necrotic damage at the start of each of its turns. Each time the slasher hits the wounded target with this attack, the damage dealt by the wound increases by 3 (1d6). The wound ends if the target regains hit points or if a creature uses an action to stanch the wound, which requires a successful DC 15 Wisdom (Medicine) check.

Legendary Actions

The relentless slasher can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The relentless slasher regains spent legendary actions at the start of its turn.

Slice. Melee or Ranged Weapon Attack: +7 to hit, reach 5 ft. or range 30/60 ft., one target. Hit: 7 (1d6 + 4) slashing damage.
Vanishing Strike (Costs 3 Actions). The slasher makes one Slasher's Knife attack. After the attack hits or misses, the slasher can teleport up to 30 feet to an unoccupied space it can see.

Relentless Slasher