Forum:Decoy Dragon effect

I m not too sure if this is is correct or not. But whenever decoy dragon is chosen as attacked target, that player with decoy dragon can summon any lv 7+ dragon? including Tyrant dragon? Do I need tribute? if so, can I tribute decoy dragon? Do u think this is a good combo on Dragon/Fire deck?

Edit: another question, I wonder if the Red eyes darkness metal dragon is bug? it is too good to be true (remove 1 tribute dragon to summon, it can revive any dragon on your graveyard 1 per turn)