The fenrir makes one bite attack against a prone Medium (Large if the fenrir is Huge, Huge if the Fenrir is Gargantuan) or smaller target. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is blinded and restrained, it has total cover against attacks and other effects outside the fenrir, and it takes 10 (3d6) acid damage at the start of each of the fenrir's turns. This damage doubles with each size increase to 20 (6d6) for Huge and 40 (12d6) for Gargantuan. The fenrir can have one target swallowed at a time when Large, two when Huge, and four when Gargantuan. If the fenrir dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone. If a target dies, the fenrir regains 10 (3d6) hit points and depending on the number of corpses consumed, gains one additional use of its Growth ability. It takes four corpses to grow from Large to Huge, and 16 corpses to grow from Huge to Gargantuan.