Horror from Below

Large aberration, chaotic neutral

Armor Class 17 (natural armor)
Hit Points 209 (22d10 + 88)
Speed 30 ft., burrow 20 ft., climb 20 ft.

STR	DEX	CON	INT	WIS	CHA
18 (+4)	10 (+0)	18 (+4)	9 (–1)	12 (+1)	4 (–3)

Damage Immunities acid, cold, fire, poison, psychic
Damage Resistances bludgeoning, piercing and slashing damage from nonmagical attacks
Condition Immunities blinded, charmed, deafened, frightened, paralyzed, petrified, poisoned, prone
Senses blindsight 60 ft., passive Perception 11
Languages Horrors from below communicate in a form of high-pitched piping, clicking, and chirping that is incomprehensible to all other creatures.
Challenge 12 (8,400 XP)

SPECIAL TRAITS

• Dimensional Instability. Anchored to a different reality, a horror shifts and wavers as if affected by a blur spell. Attacks against the horror are at disadvantage. Attacks are immune to this effect if they do not rely on sight, as with blindsight, or can see through illusion such as truesight. When slain, a horror dissolves into noxious, foul-smelling slime, and the slime itself vanishes utterly within an hour.
• Spider Climb. The horror can climb difficult surfaces, including upside-down on ceilings, without needing to make an ability check.
• Tunnel. The horror can move through solid rock at its burrow speed, leaving a cylindrical tunnel behind.

ACTIONS

• Multiattack. The horror from below makes four Pseudopod attacks. It cannot attack with pseudopods that are grappling targets, but each pseudopod with a grappled target Drain its target.
• Pseudopod. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 18 (4d6 + 4) bludgeoning damage plus 10 (3d6) necrotic damage. If the target is a creature, it is grappled (escape DC 16). Until the grapple ends, the target is restrained and the horror cannot make another attack with that pseudopod.
• Bloat. If the horror drains 100 hit points or more from its targets, it bloats to Huge size. When huge, its Armor Class is reduced to 12 and its Speed to 20. It cannot burrow, and while it can continue to inflict damage with its drain attacks, it cannot add any more temporary hit points.
• Drain. The horror can drain blood and vital fluids from any living creature grappled by one of its pseudopods. The target must make a DC 16 Constitution saving throw or take 17 (2d6 + 4) points of necrotic damage and have its maximum hit points reduced by the same amount. On a successful save, the target takes half damage and its maximum hit points is not reduced. The reduction lasts until the target takes a long rest. The target is reduced to a mummified husk and dies if its maximum hit points is reduced to 0. The horror adds half of any hit points drained as temporary hit points. This can exceed its normal maximum hit points but cannot exceed 100 temporary hit points drained (see Bloat ability).

ABOUT

The amorphous things collectively called horrors from below are the advance guard of greater powers that lurk in the twisted realms beneath the ancient dwarven realm of Ankhura. They are usually an initial assault force, attacking by surprise and burrowing through solid rock to attack defenders from all directions at once. Though they possess a native intelligence, horrors from below are nevertheless utterly incomprehensible and cannot be communicated with through any known means, mundane or arcane. They attack ferociously and without quarter, never withdrawing until destroyed.