If the karkadann moves at least 20 feet straight toward a target and then hits it with a Horn attack on the same turn, the karkadann impales the target on its horn, grappling the target if it is a Large or smaller creature (escape DC 15). Until the grapple ends, the target is restrained, takes 18 (4d8) piercing damage at the start of each of its turns, and the karkadann can't make horn attacks against other targets.