Vortash

Slime shift (passive). When hit, 2 chunks of ooze fly off within 10 feet for half of the damage taken. Both can hit creatures and deal that much damage to enemies in acid damage or add a temporary HP barrier to allies of the amount stored in the ooze. If the dragon touches this ooze instead they heal for the amount of the ooze.

Unusual Nature. The dragon doesn't require air and can fly in any weather, it can skywrite with its wings

Archival Wings. If the dragon kills a creature it turns into a ribbon of pages that accumulates in the dragons wings, the characters then learn one secret about the creature or local lore if they are not legendary. If the creature normally would be absorbed by vatash they are instead eaten and spat out as a tome containing unique skills or rarely a stat up.

Multiattack. The dragon makes one Bite attack and two Claw attacks, or three Claw attacks

Bite. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: (5d6 + 16 + 3d6) piercing damage plus 3d6 Radiant damage from Vortrex's head or 3d6 Necrotic damage from Vatash's head.

Claw. Melee Weapon Attack: +15 to hit, reach 5 ft., one target. Hit: (5d6 + 10) slashing damage. Crit on 18-20 if only claws used.

Tail. Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: (6d6 + 10) bludgeoning damage plus the target is burned by acid and takes [rollable](2d6) acid per turn.

Breath Weapon - Neo Deathflare (Recharge 5–6). The dragon exhales a blast of black and gold radiant shadow in a 80-foot cone. Each creature in the cone must make a DC 21 Constitution saving throw. On a failed save, the creature takes (8d8) Radiant damage and (8d8) Necrotic. On a successful save, the creature takes half as much damage. If the target is reduced to 0 hit points by this damage, the light bursts outwards. Every other creature within 20 feet of the target must make a Dexterity saving throw, taking (8d8) Radiant damage and (8d8) Necrotic on a failed save or half as much damage on a successful one. If the target is not reduced to 0 hit points, the light instead continues to envelope it until the end of your next turn if it failed its save. Until then, the target sheds dim light in a 10-foot radius, and attacks made against it are made with advantage.
This takes the casting head's action and the supporting head's bonus action.

Slime Sling. The dragon can throw a piece of itself, in the form of a ball of ooze, up to 90ft with it's tail. This ball of ooze is worth up to 40 HP of its health pool and has the same properties as the passive Slime Shift.

Yin Yang Beam (unlimited). A white and black beam of strange light shines down in a 5-foot-radius, 40-foot-high cylinder centered on a point within range. Until the spell ends, dim light fills the cylinder. When a creature enters the spell’s area for the first time on a turn or starts its turn there, it is engulfed in radiant and necrotic flames that cause searing pain, and it must make a Constitution saving throw. It takes 2d10 radiant  and 2d10 necrotic damage on a failed save, or half as much damage on a successful one.
A shapechanger makes its saving throw with disadvantage. If it fails, it also instantly reverts to its original form and can’t assume a different form until it leaves the spell’s light. On each of your turns after you cast this spell, you can use a bonus action to move the beam 60 feet in any direction.

Slime Scales (3/Day). The dragon becomes covered in slimy scales for as long as it maintains concentration on the effect (as if concentrating on a spell). While covered in this grey slime, the dragon has resistance to bludgeoning, piercing, and slashing damage.

Reflecting Yinang (2/day). When taking radiant or necrotic damage reflect that same amount back of the opposite element.