Shapechanger. The Fleshgait can use its action to polymorph into a Small or Medium humanoid or beast it has observed for more than a day or consumed 25% or more of, or back into its true form. Its statistics, other than its size, are the same in each form. Any clothing it is wearing is also transformed, but any equipment it is wearing or carrying isn't. It reverts to its true form if it dies.

Ambusher. The Fleshgait has advantage on attack rolls against any creature it has surprised.

Pounce. If the Fleshgait moves at least 15 feet straight towards a medium or smaller creature and then hits it with a claw attack on the same turn, the target must succeed on a DC 14 Strength Saving throw or be knocked prone. If the target is prone, the Fleshgait cane make one bite attack as a bonus action.

Hunter and Manipulator. The Fleshgait has advantage on Dexterity (Stealth) checks while in dim light or darkness, and has advantage on Charisma (Deception) checks when attempting to hide its true identity from creatures it has observed for at least 3 days with a Wisdom stat of 17 or lower. Also, the Fleshgait can cast Modify Memory at 8th level, and can target up to 5 people when casting Modify Memory, but only while outside of combat and if that memory centers around an alter-ego the Fleshgait has created. The memory modification occurs immediately after a target's failed saving throw, without the need to speak to the victim, or share a language with it.

Innate Spellcasting. The Fleshgait's innate Spellcasting ability is Charisma (Spell Save DC 15). The Fleshgait can innately cast the following spells, requiring no verbal, somatic, or material components:

3/day: Charm Person, Comprehend Languages.

1/day: Modify Memory (see Hunter and Manipulator).

Regeneration. On the start of its turn, the Fleshgait regains 5 hit points if it has at least one hit point.

Surprise Attack. If the Fleshgait surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 10 (3d6) damage from the attack.