Alriyah Vampire Jellyfish

Regeneration. The vampire jellyfish regains 10 hit points at the start of its turn if it has at least 1 hit point and isn't in sunlight. If the alriyah vampire jellyfish takes radiant damage or damage from holy water, this trait doesn't function at the start of the alriyah vampire jellyfish's next turn.

Pod Tactics. The alriyah vampire jellyfish has advantage on an attack roll against a creature if at least one of the alriyah vampire jellyfish's allies is within 5 feet of the creature and the ally isn't incapacitated.

Floater. The alriyah vampire jellyfish does not need oxygen to survive, and can float through all manners of atmosphere.

Paralyzing Body. A creature that touches the alriyah vampire jellyfish or hits it with a melee attack while within 5 feet of it takes 7 (2d6) poison damage and must make a DC 17 Constitution Saving Throw. On a success, nothing happens, but on fail, the creature is paralyzed until the start of its next turn.

Grappler. The alriyah vampire jellyfish has advantage on attack rolls against any creature grappled by it.

Unity of Form. Two alriyah vampire jellyfish can use a full turn action to fuse their forms together.
When they fuse this way, their health is increased by 20, and their size increases to Large. Large creatures now only require two tentacles, and medium and smaller creatures only need one. Additionally, they can now grabble Huge creatures with all 4 tentacles.

Multiattack. The alriyah vampire jellyfish has four tendrils which it can use to make attacks or use the grapple action.

Paralysis Stinger. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) piercing damage plus 6 (2d12) poison damage.
When a creature takes poison damage from this attack, it must make a DC 17 Constitution Saving Throw. On a success, nothing happens. On a fail, the targeted creature is Paralyzed until the end of its next turn.

Grappling Tendrils. The alriyah vampire jellyfish can use a number of tentacles to force a creature to make a DC 17 Strength Saving Throw versus the Grappled condition.
A large creature requires all 4 tentacles, a medium creature requires 2 tentacles, and small and tiny creatures only require 1.

Draining Stinger. If the alriyah vampire jellyfish hits with Paralysis Stinger on a target that's already paralyzed, they can instead choose to recover health equal to the poison damage rolled instead of inflicting that damage.