Byakhee

Accelerated Star Travel. The byakhee’s hune organ allows it to survive and fly in space at incredible speeds. Travel times vary, but it can generally arrive within the same solar system in 3d20 hours, or to another star system within 3d20 days.
Unbreathing. The byakhee doesn’t need to breathe.
Unknowable Form. The byakhee’s form cannot be grasped by sane mortals’ minds. The byakhee is considered lightly obscured by all creatures with Intelligence scores of 3 or higher that are not aberrations, celestials, elementals, fey, fiends, or suffering from some form of insanity or confusion. Attack rolls by affected creatures against the byakhee have disadvantage.
Void Sight. Magical darkness doesn’t impede the byakhee’s darkvision.

Multiattack. The byakhee makes two attacks: one blood drain
and one with its claws.

Blood Drain. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage and if the target is a Large or smaller creature other than a construct, elemental, or undead, it must succeed on a DC 13 Strength saving throw or be grappled (escape DC 13). Until this grapple ends, the target is restrained, and the byakhee can’t use blood drain again. When the creature begins its turn grappled by the byakhee, the creature loses 8 (1d8 + 4) hit points from blood loss.

Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target.
Hit: 11 (2d6 + 4) slashing damage and if the target is a Large or smaller creature, it must succeed on a DC 13 Strength saving throw or be grappled (escape DC 13). Until this grapple ends, the target is restrained, and the byakhee can’t claw another target. When the creature begins its turn grappled by the byakhee, the creature loses 8 (1d8 + 4) hit points from blood loss.

Shriek (1/day). The byakhee issues a horrific shriek that penetrates both space and time. At the end of the byakhee’s turn, another byakhee is called from another place and time, appearing within 5 feet of the shrieking byakhee. It rolls initiative immediately and takes its own turns. The newly arrived byakhee cannot shriek when called this way. The called byakhee returns from whence it came after 24 hours or when it is reduced to 0 hit points.