Forum:Power Invader effect?

If my opponent has 2 or more monsters, one of them being Stardust Dragon/Assault Mode and I summon Power Invader without tributing can Stardust/Assault negate it? Is the condition that it can be summoned without tributing treated as an effect that has the be activated? 99.229.208.177 (talk) 23:38, January 1, 2012 (UTC)