Eldritch Thing

Medium aberration, chaotic evil

Armor Class 16
Hit Points 115 (12d10 + 50)
Speed 30 ft.

Str	Dex	Con	Int	Wis	Cha
15 (+2)	16 (+3)	20 (+5)	10 (+0)	13 (+1)	14 (+2)

Saving Throws Constitution +9
Skills Athletics +6, Deception +6, Stealth +7
Damage Resistances bludgeoning and piercing from nonmagical attacks that aren’t silvered
Damage Immunities cold, slashing
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
Senses blindsight 60 ft. (blind beyond this radius), passive Perception 11
Languages the languages of any creatures it has assimilated
Challenge 10 (5,900 XP)
Proficiency Bonus +4

Special Traits

• Amorphous. In its true form, the eldritch thing can move through a space as narrow as 1 foot wide without squeezing.
• Shapeshifter. The eldritch thing can use its action to polymorph into a Small or Medium creature it has assimilated, or back into its true form. Its statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn’t transformed. It reverts to its true form if it dies.

Actions

• Multiattack. The eldritch thing makes two tentacle attacks or uses its Assimilate ability.
• Assimilate. As an action, the eldritch thing chooses a creature it has grappled with 0 hit points and absorbs them into its form. The target instantly dies, its body dissolving into the mass of the eldritch thing. The victim’s body and soul are destroyed entirely by this process; only a wish spell can return the victim to life. Once the eldritch thing has absorbed its victim’s body, it learns all the languages the target knows and gains all its proficiencies. It also recalls the victim’s life, experiences, and personality to an uncanny degree. When the eldritch thing shapeshifts into a creature it has assimilated, it has advantage on Charisma (Deception) checks to trick people into believing it is the victim.
• Tentacle. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 17 (4d6 + 3) bludgeoning damage plus 7 (2d6) necrotic damage. If the target is Medium or smaller, it is grappled (escape DC 18) and restrained until the grapple ends. The eldritch thing has two tentacles, each of which can grapple one target.

Reactions

• Split. When an eldritch thing that is Medium is subjected to slashing damage, it splits into two Small eldritch things if it has at least 10 hit points. Each new eldritch thing has hit points equal to half the original thing’s, rounded down. Small eldritch things have Intelligence of 5 (-3). Once the have assimilated a Medium creature or three Small creatures, they grow to Medium size and have game statistics as listed above.

About

An eldritch thing is a shapeshifting alien creature found in arctic climes that kills and assimilates living creatures. Whether it fell from the sky or has always lay dormant in the ice is unknown. When living creatures unearth it, usually by accident, it awakens.

Once awakened, an eldritch thing hunts living prey to assimilate. Its true form is as an amorphous blob, not unlike a pudding or ooze, but made of an amalgam of clearly organic tissue, body parts, and organs.

When it hunts, it lies in wait for a target to be alone and then attempts to consume them.

The eldritch thing attacks a foe by grappling it with tentacles that digest its prey. Once it has consumed a victim, it can shapeshift into the victim’s form, creating an eerily accurate mimicry of the original, down to language, personality, and memories. The eldritch thing then uses its new form as camouflage and works to isolate another living target, so that it can attempt to consume them as well.

Eldritch things reproduce by fission.

When they take on enough mass – usually several full-sized humanoids, for example – they split into two and each go their own way. This fission can be forced, as well, when an eldritch thing takes slashing damage.

The resulting splits each become an autonomous eldritch thing.