Keen Smell. The troll has advantage on Wisdom (Perception) checks that rely on smell.

Regeneration. The troll regains hit points equal to the damage it dealt during its last turn at the start of its turn. If it did less than 15 damage, then it regains 15 hit points instead. If the troll takes acid or fire damage, this trait doesn't function at the start of the troll's next turn. The troll dies only if it starts its turn with 0 hit points and doesn't regenerate.

Mutations. When the troll regains hit points using its regeneration trait, roll a d6. On a 5-6, the troll mutates. Roll a d4. The troll gains the effect correlating to the result:

1. The troll grows one head.
2. The troll grows one arm.
3. The troll grows one tendril.
4. The troll's legs grow longer, increasing its speed by 5 feet.

Folds of Skin. The troll has massive folds of thick skin due to its age. The skin provides an extra layer of protection to the troll, having AC 20 (natural armor) and 42 hit points. The skin has resistance to all damage except for bludgeoning, piercing, and slashing damage dealt by magical weapons and force damage. While covered by the skin, it has total cover, but can still see. The Regeneration trait also applies to the skin, and regenerates damage equal to the damage dealt by the troll itself.

If the skin is destroyed, it regenerates after 1d4 hours.

Innate Spellcasting. The troll's innate spellcasting ability is Constitution (spell save DC 19). It can innately cast the following spells, requiring no somatic or material components:

At will: infestation, gust, poison spray, primal savagery

3/day each: goodberry, inflict wounds, [spell[haste[/spell]

1/day each: vampiric touch (at 5th level), inflict wounds (at 5th level), blight (at 5th level), cloudkill

Bane of Giants. The troll deals double damage to other giants.

Loathsome Limbs. Whenever the troll takes at least 8 bludgeoning or slashing damage at one time, roll a d20 to determine what else happens to it:

1–6: One leg is severed from the troll if it has any legs left.

8–14: One arm is severed from the troll if it has any arms left.

15-18: One tendril is severed from the troll if it has any tendrils left.

19–20: The troll is decapitated.

A severed part acts on the troll's initiative and has its own action and movement. A severed part has AC 15 and 43 hit points, and has blindsight with a range of 30 ft.

A severed leg is unable to attack and has a speed of 10 feet.

A severed arm has a speed of 10 feet and can make one claw attack on its turn, with a -2 penalty on the attack roll. Each time the troll loses an arm, it loses a claw attack.

A severed tendril has a speed of 10 feet and a burrowing speed of 10 feet and can make one tendril attack on its turn, with a -2 penalty on the attack roll. Each time the troll loses a tendril, it loses a tendril attack.

If its head is severed, the troll loses its bite and booming voice attack and its body is blinded unless the head can see it. The severed head has a speed of 0 feet. It can make a bite attack, but only against a target in its space. It can also make a booming voice attack.

The troll's speed is halved if it's missing a leg. If it loses both legs, it falls prone. If it has both arms, it can crawl. With only one arm, it can still crawl, but its speed is halved. With no arms or legs, its speed is 0 feet, and it can't benefit from bonuses to speed.

After one turn, the troll's limbs grow back, and the severed limbs remain as they are. The troll may take a bonus action to send a message to its limbs. When it does so, the limbs will try to attach themselves to the troll as quickly as possible if they can sense the troll with blindsight. Arms and tendrils will attempt to carry severed heads. When doing so, they lose their attack. 

If a body part is within 10 ft. of the troll, it may take an action to reattach it to its body (both the troll and the body part may do so). The troll gains temporary hit points equal to the hit points of the severed limb and gains the attacks of the severed limb. All attack roll penalties that the limb possessed disappear.

If the troll has two or more heads, then it gains the following trait:

Two Heads. The troll has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, stunned, and knocked unconscious.

Grasping Tendrils. Each tendril the troll possesses can be attacked (AC 20; 10 hit points; damage immunities and resistances of the troll plus immunity to psychic damage). Destroying a tendril deals no damage to the troll, which can extrude a replacement tendril on its next turn. A tendril can also be broken if a creature takes an action and succeeds on a DC 15 Strength check against it.

Stench. Any creature that starts its turn within 10 feet of the troll must succeed on a DC 18 Constitution saving throw or be poisoned until the start of its next turn. On a successful saving throw, the creature is immune to the troll's Stench for 24 hours.

Spread Essence. Each turn as a bonus action, the troll touches a willing creature of its choice within 10 feet of it. The creature gains a trait of the troll of the troll's choice, provided it did not have the exact same trait before.

Multiattack. The troll makes a varied number of attacks: one with its bite for each of its heads, one with its claws for each of its arms, one with its tendrils for each of its available tendrils, one with its booming voice for each of its heads (if recharged), one with its whirlwind of claws (if recharged), and one with its reel (if it has any creatures grappled.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 22 (4d8 + 3) piercing damage and 6 (1d12+2) necrotic damage.

Claw. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 24 (8d6 + 4) slashing damage and 6 (1d12+2) necrotic damage.

Booming Voice (Recharge 4-6). The hideous voice of the troll booms in a 120-foot radius. All creatures in that area must make a DC 19 Constitution saving throw, taking 18 (6d6 + 4) necrotic damage and be frightened of the troll and any other trolls for 1 minute. On a success, the creature only takes half the damage and is not frightened.

Creatures within 30 ft. of the troll must make a DC 20 Constitution saving throw or be deafened for 1 minute.

A frightened creature can repeat the saving throw on each of their turns, ending the effect early on a success.

This action is not impeded by any effects that induce silence (such as silence). Any ongoing effects that induce silence inside the range of this action end.

Whirlwind of Claws (Recharge 5–6) (Only usable is the troll has three or more arms.) Each creature within 10 feet of the troll must make a DC 19 Dexterity saving throw, taking 22 (4d10+3) slashing damage multiplied by the number of arms the troll possesses on a failed save, or half as much damage on a successful one.

Tendril. Melee Weapon Attack: +13 to hit, reach 50 ft., one creature. Hit: The target is grappled (escape DC 15). Until the grapple ends, the target is restrained and has disadvantage on Strength checks and Strength saving throws, and the troll can't use the same tendril on another target.

Reel. The troll pulls each creature grappled by it up to 25 feet straight toward it.

Focus Skin. When an attack roll against the troll succeeds and it has its skin, it may use its reaction to choose from the following choices:

• The troll only has three-quarters cover and the area where the attack was aimed has an AC of 23. The attacker must reroll their attack roll.
• The troll only has half cover and the area where the attack was aimed has an AC of 27. The attacker must reroll their attack roll.
• The troll loses its cover, and the area where the attack was aimed has an AC of 30. The attacker must reroll their attack roll.

Abecsi can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. Abecsi regains spent legendary actions at the start of its turn.

Claws. The troll makes two attacks with its claws.

Tendrils. The troll makes two attacks with its tendrils and makes one reel attack if it has any targets grappled.

Feral Boost (Costs 3 Actions). The troll recharges all of its attacks and uses one of them.

Spellcast (Costs 2 Actions). The troll casts one of the following spells: infestation, gust, poison spray, primal savagery