Ice Hydras are alpha predators of the Equestrian Tundra with incredible regenerative capability. When one head is severed, two grow back in its place. The only successful method of destruction is complete molecular dissolution or starvation. They are thankfully rare.
Lozenge encounters an adult hydra guarding her nest in the Department of Life compound. She 'dispatched' the creature by using an experimental surgical laser to sever its head repeatedly, until it became a writing mass of heads incapable of coherent function. It, and its young, presumably starved afterwards.