Discovering this device requires the player to have the blueprint unlocked from the cave goblin technology tree, and level 50 Invention. Success in creating the blueprints earns 18,257 Invention experience. They can hit up to 9 targets in a 3x3 area. They cannot be picked up again from the ground after being thrown and Ava's devices (attractor, accumulator, alerter) do not return them. Sacrifice will deal area damage, but would only heal according to the damage taken by the main target. Damage over time effects will be applied to all targets initially in the area.