Greater mimics are a larger, more intelligent version of the common mimic with limited magical powers. Most sages agree that they are not a separate species, but are ordinary mimic of exceptional size and cunning that have been mutated by subterranean magical forces.
A greater mimic has the same personality as its smaller kin, being interested solely in its own security, food, and wealth - in that order. They may form alliances with other creatures, but will dispassionately devour their allies the instant the relationship ceases being useful.
Greater mimics speak Common and Undercommon. They usually "speak" by creating an illusion of a humanoid, but can talk with their actual mouths.
Combat
A greater mimic imitates a room or small cavern and tries to lure prey into stepping inside this chamber, often using illusions or treasure as bait. Once some victims enter this chamber, the mimic snaps the entrance close and fastens onto its prey with adhesive, then collapses its body and attempts to crush its victims to death. Should opponents refuse to enter its chamber, a greater mimic can exude adhesive-coated pseudopods and try to drag them into its crushing interior.
A greater mimic will fight to the death if it has no alternative, but prefers to negotiate surrender or withdrawal when a foe threatens its life. They may offer treasure (or demand tribute!) as additional inducement.