🛸 ​The Thing 🛸​

Assimilation: When a humanoid dies within 10 feet of The Thing, the creature may begin assimilation.

After 1 minute:

• the corpse becomes biologically identical to the original creature,
• including voice, memories fragments, and mannerisms.

Only:

• Greater Restoration,
• Wish,
• or destroying all infected tissue

reveals or prevents the transformation.

Perfect Mimicry: The Thing has advantage on all Deception checks made to impersonate absorbed creatures.

A creature interacting with The Thing cannot determine its true nature unless:

• magic is used,
• obvious physical inconsistencies appear,
• or The Thing becomes stressed or injured.

Autonomous Flesh: Every part of The Thing is alive independently.

Whenever it takes:

• fire damage,
• critical hit damage,
• or more than 25 damage in one turn,

roll a d6:

Fear of Fire: The Thing instinctively fears fire.

When it takes fire damage:

• it has disadvantage on attack rolls until the end of its next turn,
• and cannot use Perfect Mimicry for 1 round.

Multiattack: The Thing makes 3 attacks.

Tendril Strike. Melee Weapon Attack: +9 to hit, reach 15 ft. Hit: 2d10 + 5 slashing damage plus 2d6 acid damage.

The target is grappled (escape DC 16).

Consume Biomass: The Thing targets one grappled creature. The target must make a DC 17 Constitution saving throw.

On a failure:

• take 6d8 necrotic damage
• maximum HP reduced by the same amount

If this reduces the target to 0 HP: assimilation begins immediately.

Reveal True Form (Recharge 10 minute): The Thing loses all restraint. Its body erupts into a nightmare of: jaws, limbs, eyes, exposed organs, and partially transformed victims.

Every creature within 30 ft. must make a DC 17 Wisdom saving throw.

On a failure:

• take 4d10 psychic damage
• become frightened for 1 minute

A frightened creature may repeat the save at the end of each turn.

Opportunity Attack. 

Crawl Away: When reduced below half HP, The Thing may detach part of itself.

A Small fragment escapes with:

• 1 HP,
• stealth advantage,
• and the ability to begin assimilation again later.

Killing the main body does not guarantee the organism is dead.

Infection:  A creature damaged by Consume Biomass must secretly roll a Constitution save during the next long rest.

On a failure:

• a microscopic fragment survives inside them.

The DM may secretly decide:

• strange behavior begins,
• dreams worsen,
• animals react aggressively,
• blood moves unnaturally.

The character may already no longer be entirely themselves.