Gravity Warrior [PRC1-EN020] Secret Rare

1 Tuner + 1 or more non-Tuner monsters When this card is Synchro Summoned: It gains 300 ATK for each face-up monster your opponent controls. Once per turn, during your opponent's Battle Phase: You can target 1 Defense Position monster your opponent controls; change it to face-up Attack Position, also it must attack this turn, if able.