Bloomspreader Hulk

Regeneration: The hulk regains 10 hit points at the start of its turn if it has not taken fire damage since the end of its last turn.

Raidboss resistance: the hulk has advantage on saving throws against spells or other magical effects. It is immune to any effect that would teleport it or alter its shape.

legendary Resistance (3/day): Whenever the hulk fails a saving throw, it may choose to succeed instead.

Hazy Aura: While the hulk is conscious, it has an aura of pollen in a 10 foot radius around it. Non Fey creatures that end their turn in the aura must make a DC 13 constitution saving throw or become unconscious for one minute, until they take damage, or are shaken awake by another creature as an action. This effect does not stack with other Hazy Aura effects.

Mechanics:

Bloomshield: the hulk begins combat with a glowing green shield surrounding it giving it resistance to all damage except fire damage. This shield can only be dispelled by hitting it with a Blossoming Charge and returns at the end of a Damage Phase. 

Bloom Carrier: At initiative count 20, one Bloom Carrier will appear on the battlefield within 30 feet of the hulk. a Bloom Carrier is a glowing green Awakened Shrub that goes on initiative count 20 and cannot take actions besides disengage and dash but will move away from any enemy creatures. It cannot willingly move further than 60 feet away from the hulk. Killing it drops a Blossoming Charge.

Blossoming Charge: When an bloom carrier is killed, it drops a Blossoming Charge in its space. A creature may pick up a blossoming charge by moving into its space and may throw it as an attack action or bonus action. When a creature picks up a blossoming charge it regains 10 hit points and its movement speed is increased by 30 feet while it holds the charge. Throwing the charge at another creature besides the hulk causes that creature to regain 5 hit points and gain the bonus movement speed. Throwing the blossoming charge at the hulk causes the shield to drop until the end of the throwing creatures next turn, beginning a Damage Phase.

Damage Phase: During a damage phase, the hulks Bloomshield is deactivated, it takes all damage as normal, is vulnerable to fire damage, and cannot use legendary actions. It also drops all creatures it has grappled or engulfed, placing them in spaces of its choice within 5 feet of it. The damage phase lasts until the end of the next turn of the creature that started it. After a damage phase, the Bloomshield is reactivated. 

Multiattack. The hulk makes two slam attacks.

Slam. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 6) bludgeoning damage. The target must succeed a DC 15 strength saving throw or be grappled by the hulk (escape DC 15 str). The hulk can only grapple 2 creatures at once.

Engulf. The hulk engulfs a Medium or smaller creature grappled by it. The engulfed target is blinded, restrained, and unable to breathe, and it must succeed on a DC 14 Constitution saving throw at the start of each of the mound’s turns or take 13 (2d8 + 4); bludgeoning damage. If the hulk moves, the engulfed target moves with it. The hulk can have only one creature engulfed at a time. If the hulk takes 20 damage from a single source, the engulfed creature is freed and moves to an unoccupied space of their choice within 5 feet of the hulk.

The hulk 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. The hulk regains spent legendary actions at the start of its turn.

Move: The hulk moves up to its movement speed

Slam: the hulk makes a slam attack

Root Explosion (2 actions): All creatures within 10 feet of the hulk must make a DC 15 dexterity saving throw or take 25 (6d6) piercing damage and be launched 30 feet away from the Hulk. Creatures who save take half and are not launched.

Engulf (2 actions): the hulk uses the Engulf action on a creature it has grappled.