Aura of Madness (120 ft.). Any non-undead creature that starts its turn within 120 ft. must succeed on a DC 25 Wisdom saving throw or suffer short-term madness for 1 minute (roll on DMG Madness table). A creature that succeeds is immune to this effect for 24 hours.

Rotting Divinity. When Haug moves, the ground within 30 ft. becomes difficult terrain and fills with mud and acid. Any creature that starts its turn in the mud takes 28 (8d6) acid damage and must succeed on a DC 25 Strength save or be restrained.

Insane Regeneration. Haug regains 30 hit points at the start of his turn unless he took radiant or psychic damage since his last turn.

Aura of Decay. Healing magic within 60 ft. of Haug restores only half the normal amount.

Legendary Resistance (5/Day). If Haug fails a saving throw, he can choose to succeed instead.

Multiattack. Haug makes three attacks: two with his Putrid Fist and one with Vomiting Swamp.

Putrid Fist. Melee Weapon Attack: +18 to hit, reach 20 ft., one target.
Hit: 45 (6d10+10) bludgeoning damage plus 21 (6d6) acid damage.

Vomiting Swamp (Recharge 5–6). Haug vomits forth a 90-ft. cone of rotting sludge. Each creature must make a DC 26 Dexterity save, taking 91 (26d6) acid and poison damage on a failed save, or half as much on a success. The area becomes deep, corrosive mud (difficult terrain) for 1 minute.

Devour the Weak. Haug grabs one Large or smaller creature within 10 ft. and swallows it whole. The swallowed creature is blinded, restrained, and takes 42 (12d6) acid damage at the start of each of Haug’s turns. If Haug takes 50 damage or more on a single turn from a creature inside him, he must succeed on a DC 25 Con save or regurgitate all swallowed creatures.

Haug can take 3 legendary actions, choosing from the options below:

1. Crushing Stomp. Haug stomps the ground, causing a shockwave. Each creature within 20 ft. must make a DC 25 Dexterity save or take 35 (10d6) bludgeoning damage and be knocked prone.

2. Mud Tendrils. Haug causes tendrils of mud to rise from the ground. Each creature of his choice within 60 ft. must make a DC 25 Strength save or be grappled (escape DC 25).

3. Whispers of Rot (Costs 2). Haug’s maddening laughter echoes. All creatures of his choice within 120 ft. must make a DC 25 Wisdom save or take 27 (6d8) psychic damage and be confused (as the confusion spell) until the end of their next turn.

Mythic Trait — The Swamp Awakens

When Haug is reduced to 0 HP, he sinks into the mud and merges with his domain. He regains 500 HP, and the entire battlefield becomes the Swamp of Oblivion for the remainder of the fight.

Effects of the Swamp:

• The ground becomes knee-deep acid mud (difficult terrain).

• The air becomes toxic; creatures that breathe take 14 (4d6) poison damage each round.

• Every round on initiative 20, a random effect occurs:

  1. A Mud Titan (CR 20) rises and fights for Haug.

  2. A wave of filth crashes over the area, forcing a DC 25 Dex save or be knocked prone.

  3. All creatures that aren’t undead or divine take 28 (8d6) necrotic damage as the swamp drains their life.