Coza

Draining Haze. The fog created as  a part of Coza's regional effects is far from normal fog. When a creature within the fog is healed, it gets half the normal amount it should. The other half of the healing is applied to Coza as temporary hit points. Temporary hit points gained in this way can stack to a maximum of 30. If Coza has any temporary  hit points at initiative 0, then they are converted to healing.

Immutable & Immovable. Coza is immune to any spell or effect that would alter their form or move their body. They also cannot be teleported, plane shifted, or banished against their will.

Multiattack. Coza makes 3 Vorpal Vine attacks and uses Wringing Roots, if it is available.

Vorpal Vine. Melee Weapon Attack: +8 to hit, reach 90 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage, and the target is Grappled (escape DC 16 (+2 per vine)). While the target Grappled in this way they are unable to breathe, and Coza can move them 30 feet any any direction at the beginning of the tree's turn. They can suspend the target a maximum of 60 feet in the air. Until the grapple ends, a target takes 11 bludgeoning damage at the start of each of their turns.

Up to 3 vines can grab the same creature. If a creature is Grappled by 2 or more vines they take 18 bludgeoning damage at the start of each of their turns. If a creature is Grappled by 3 vines they are also Restrained. A creature that succees on escaping the vines escapes all vines at once. Alternatively, an ally of a creature Grappled by Coza's vines can attempt to attack them directly. They must make an attack against the vines, which have an AC of 16 (+2 per vine), ending the grapple on a hit.

Wringing Roots (Recharge 5-6). Coza chooses one target within 60 feet of his trunk, they must make a DC 20 Dexterity saving throw, or take 15 (2d10 +4) bludgeoning damage and become Restrained. Coza cannot used this ability on a target not touching the ground, and while the target is Restrained in this way they cannot be suspended by Vorpal Vine. A creature may remake the saving throw at the end of each of their turns, ending the effect on a success.

A creature both Restrained by this ability and Grappled by Vorpal Vines takes 20 force damage at the beginning of its turn, instead of the damage given by Vorpal Vines. A creature reduced to 0 hit points by this damage is beheaded. 

Coza can take 3 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. Coza regains spent legendary actions at the start of their turn.

Legendary Resilience (Costs 2 Actions). Coza ends 1 spell or harmful effect currently affecting them. They can use this action even if they are incapacitated, and must use this action if they are currently charmed.

Fog Focus (Costs 2 Actions). Coza chooses a creature within 60 feet of their trunk. The creature must make a DC 17 Constitution saving throw or gain 1 level of exhaustion.

Grab. Coza makes an attack with their Vorpal Vines.

Drop. Coza releases a creature they have Grappled with their Vorpal Vines.