The Shapeshifter

Medium aberration (shapechanger), chaotic evil

Armor Class

17 (natural armor)

Hit Points

190 (20d8 + 100)

Speed

40 ft.

Skills

Deception +9, Perception +9, Stealth +9, Survival +9

Damage Resistances

bludgeoning, piercing, and slashing from nonmagical weapons

Damage Vulnerabilities

fire

Damage Immunities

cold

Condition Immunities

charmed, exhaustion

Senses

darkvision 60 ft.

Languages

the languages of the form it has assumed

Challenge

15

Ambusher

In the first round of a combat, the shapeshifter has advantage on attack rolls against any creature it surprises.

Assume Form

The shapeshifter can assume the appearance of any Medium (or smaller) humanoid or beast it has eaten. It also feels and sounds exactly like the victim, speaking the languages it knows. Only a successful DC 18 Wisdom (Insight) check will reveal it to be a fake.

Magic Resistance

The shapeshifter has advantage on saving throws against spells and other magical effects.

Regeneration

The shapeshifter regains 10 hit points at the beginning of each of its turns. It is only destroyed if it starts its turn with 0 hit points and doesn't regenerate.

Spider Climb

The shapeshifter can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Actions

Multiattack

The shapeshifter can make one attack with its bite and two attacks with tendrils that emerge from inside its body.

Bite

Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 18 (3d8 + 5) piercing damage.

Tendrils

Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 18 (3d8 + 5) slashing damage.