Huge elemental, any evil

Armor Class 18 (natural)
Hit Points 382 (45d12+90)
Speed 40 ft., fly 80 ft.

23 (+6) 14 (+2) 15 (+2) 19 (+4) 17 (+3) 15 (+2)

Saving Throws Str +12, Con +8, Wis +9
Damage Immunities fire
Condition Immunities frightened, grappled, petrified, poisoned, restrained
Damage Resistances lightning, thunder, bludgeoning, piercing, and slashing from non-magical weapons
Senses tremorsense 30 ft., darkvision 120 ft., passive Perception 13
Languages Primordial
Challenge 20 (25,000 XP)


  • Magic Resistance. The oonlulth has advantage on saving throws against spells and other magical effects.
  • Aura of Darkness. A thick cloud of magic ash surrounds the oonlulth. The area within 30 feet of the oonlulth is considered darkness. Non-magical light is blotted out. Magical light can penetrate the area but only creates dim lighting.
  • Lightning Storm. When the creature manifests, the air around it becomes heated and charged. Each round, one creature within 30 feet of the oonlulth chosen at random is struck by lightning. The target can make a Dexterity save (DC 18), taking 22 (4d10) lightning damage on a failed save, or half as much on a successful save.
  • Regeneration. The oonlulth regenerates 20 hit points at the start of its turn as long as it is conscious.


  • Multiattack. The oonlulth strikes three times with its hammer each turn.
  • Hammer. Melee Weapon Attack: +12 to hit, reach 15 ft., one creature. Hit: 22 (3d10+6) bludgeoning damage. This weapon is considered to be magical. Further, the target must make a Constitution save (DC 19). If the target fails the save, they suffer a crippling wound, effectively giving them a level of fatigue.


The oonlulth have no true shape or form. Crushed by the weight of the world, their essence alone drifted through dark fissures and cracks in the stone; however, in the long years since their uprooting, the oonlulth have learned to take form. When in the lonely dark they are nothing more than a cloud of shadow, dark soot that flows across the ground in undulating waves. But when they take form they rise up, twisting their knowledge the under-deep, taking form with flame, lightning, and ash. They stand some 30 feet tall when fully roused with bodies vaguely humanoid. The ash that is their substance moves constantly, like clouds of dark smoke. As they walk, the ash rises in clouds and tumbles about their claw-like feet. They burn with a fire within, the sickly, white flames consuming their substance, making ever more ash for their form. They have no facial features, only the shadow of eyes, and a gaping mouth filled with an echoing white fire. In battle, the oonlulth prefer to wield a huge black hammer. Shaped after a sledgehammer this massive cudgel delivers immense damage. As soon as they take shape, the hammer appears in their hand, made of the same ash and flame as their bodies are.

Horrors of the Deep. The oonlulth are spirits of the deep. They dwell in deep caves, or dungeons long abandoned. They generally have no form or shape, though occasionally an oonlulth assumes a form and retains it. They linger in dark places, almost always large caverns. Their minds cannot imagine much beyond a vague form so when they do take shape, it is quick and always vaguely humanoid.

Haters of Life. They have no lusts, nor drive, nor are they possessed of any worldly thought other than to smother all things that live in their ash and fire. There are no worldly awards they seek, their treasure is usually scattered throughout their halls, left on the bodies of men and elves, dwarves or monsters that they have slain.

Aura of Ash. When the Oonlulth takes shape, a cloud of thick ash forms around it. This cloud blots out light, warms the air, and charges the area around the creature with electricity. The cloud immediately dissipates of the creature is slain.

Section 15: Copyright Notice

5th Edition Monsters & Treasure of Airhde, 1st Printing, Copyright 2021, Troll Lord Games; Author Stephen Chenault & Jason Vey

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