Mercurial
Level 2Attacks
Abilities
The mercurial takes on the appearance of any Small or Medium humanoid. This transformation allows for significant detail and can reproduce the features of a specific individual, but the mercurial retains a shiny, liquid-metal appearance that renders the transformation unsuitable as a disguise unless they're impersonating another mercurial. It doesn't change the mercurial's Speed or the attack and damage bonuses of their Strikes, but it does allow them to transform their limbs into metal tools or melee weapons, potentially changing the damage type dealt by their Strikes. The monster changes its shape indefinitely. It can use this action again to return to its natural shape or adopt a new shape. Unless otherwise noted, a monster cannot use Change Shape to appear as a specific individual. Using Change Shape counts as creating a disguise for the Impersonate use of Deception. The monster's transformation automatically defeats Perception DCs to determine whether the creature is a member of the ancestry or creature type into which it transformed, and it gains a +4 status bonus to its Deception DC to prevent others from seeing through its disguise. Change Shape abilities specify what shapes the monster can adopt. The monster doesn't gain any special abilities of the new shape, only its physical form. For example, in each shape, it replaces its normal Speeds and Strikes, and might potentially change its senses or size. Any changes are listed in its stat block.
Description
Some of the most populous denizens of the Plane of Metal, mercurials are weird creatures of liquid metal known for changing their features, chemical compositions, and temperaments with equal frequency. Excitable, curious, and friendly, mercurials are quick to offer assistance to extraplanar beings, but their volatile personalities can make them unreliable allies.
Metal elementals can manifest in a wide variety of different forms, from shapeless amalgams of different metals to humanoid and beast-like monstrosities.
Metal Forms
Though metal elementals are made almost entirely of metal, most are composed of layers of different metals in tiny fragments, as complex as a body of flesh or plant matter. Many of these metals are rusted or decayed from the natural, slow entropy of the Plane of Metal.
Many Faces, Many Names
As immortal beings with comparatively short attention spans, mercurials invariably become bored with their current identities sooner or later and seek a change by adopting a new face and persona. To avoid confusion among friends and acquaintances, a mercurial's name typically consists not only of their current moniker, but a list of the last few names used, presented in chronological order as far back as the mercurial can remember.