Bending the rules with card of scarifies in yugioh?

"card of scarifies- Draw 2 cards, if the combined ATK of all your face-up Attack Position monsters (minimum 2) is less than the ATK of your opponent's face-up monster with the lowest ATK. You cannot Summon or change Battle Position the turn you activate this card". lets say i have more then two monsters can i still activate this card? 2nd question. can i still activate this card on my opponents turn and even in a chain?. basically i dont care much for not being able to summon or change battle position because my monsters have high attack pts. i just want a hand advantage. im not concerned if my monsters get destroyed either, i just wanna increase my draw power. an example. if my opponent has a face up stardust dragon and i have 3 face up vorse raiders can i still activate this card even though my monster have higher combined attack then stardust dragon? so that's my question. so can i do the fallowing accordingly?