An implant assembly comprises an elongated pusher member, and an implantable device (e.g., a vaso-occlusive device) mounted to the distal end of the pusher member. The implant assembly further comprises an electrolytically severable joint disposed on the pusher member, wherein the implantable device detaches from the pusher member when the severable joint is severed, and a return electrode carried by the distal end of the pusher member (e.g., a coil disposed about the pusher member) in proximity to, but electrically isolated from, the severable joint. The implant assembly further comprises a terminal carried by the proximal end of the pusher member in electrical communication with the severable joint.