Formed entirely of shadowstuff, Ranunculus passes through matter and living things. While objects are unaffected by its passing, living creatures, when struck, are stunned and descend instantly into madness, effectively removing them from any battle. Upon spoken command, Ranunculus will instantly return to its owner’s hand.
A cave with weapons sunken into the walls, blades sticking out of the floor and ceiling, and so on. Possibly, any weapon used in it could be torn out of the hand and sink into the stone.