Fossil Dragon Skullgios [SGX4-END21] Common

1 Rock monster + 1 Level 7 or higher monster in your opponent's GY
Must first be Special Summoned with "Fossil Fusion". Before damage calculation, if this card battles an opponent's monster: You can switch the current ATK and DEF of that opponent's monster until the end of that Damage Step. If this card attacks a Defense Position monster, inflict piercing battle damage. If this Fusion Summoned card battles an opponent's monster, any battle damage it inflicts to your opponent is doubled.