Seneferu's Golden Lotus (3.5e Equipment)
From D&D Wiki
The Golden Lotus: This beautiful golden lotus, inlaid with malachite, is actually an intricate hair clasp. When worn, it appears to have no special properties, and radiates no aura. However, when this hair clasp is removed and thrown into a body of water, the owner is empowered with a control water (CL 15) spell that she may use on the body of water the clasp is currently in.
If the clasp is removed and discarded, or is otherwise lost, the person responsible for the loss of the clasp is immediately attacked by a banshee (as per Monster Manual II). The banshee will stay in the area where the clasp was lost, attacking anything that moves through the area. If the owner recovers the clasp, the banshee will disappear into the mists.