If you control no monsters, you can Special Summon this card (from your hand). You can only Special Summon "Double-Headed Dino King Rex" once per turn this way. If this card is Normal or Special Summoned: You can target 1 monster on the field with less ATK than the total ATK of all Dinosaur monsters you control; destroy it. You can only use this effect of "Double-Headed Dino King Rex" once per turn.