Urubonus, the Avatar of Malice

All monsters your opponent controls lose 300 ATK/DEF. You can only use each of the following effects of "Urubonus, the Avatar of Malice" once per turn. You can Tribute 1 Reptile monster; Special Summon this card from your hand. You can Tribute 1 monster; all face-up monsters your opponent currently controls lose ATK/DEF equal to the Tributed monster's original ATK, until the end of this turn.