A Goomba's main form of attack is walking into their opponents. Rarely, a Goomba walks off a ledge and falls on its enemy. A Goomba's only real strength is that it works in large groups to attack an enemy. This forces the opponent to be much more cautious as he or she fights the group. In some games, Goombas have additional attacks such as biting and spitting thorns from their mouths in Super Mario RPG: Legend of the Seven Stars. In the Mario & Luigi series, various Goombas attack by charging with a headbutt, biting, rolling, and kicking. In Paper Mario and Paper Mario: The Thousand-Year Door, Goombas gain the ability to headbonk enemies, which also returns in Mario & Luigi: Superstar Saga + Bowser's Minions.