Hoard Mimic

Hoard Mimic
Kin to the common mimic described in the Monster Manual, hoard mimics are among the oldest and most cunning of their kind. A hoard mimic's massive, amorphous form and shape-shifting prowess allow it to take on the semblance of a vast trove of treasures, not just a single object. Like smaller mimics, hoard mimics exude adhesive goo to trap prey. They can also vent a fine, caustic mist from their pores that burns and blinds creatures caught in it.
Hoard mimics are so named because many enter into partnerships with dragons, each one serving as a false hoard in a dragon's lair to draw unwitting intruders away from the real riches—and into the mimic's maw. If faced with unexpectedly fierce opposition, though, a hoard mimic might offer information about the true hoard in exchange for its life.