Forum:Decoy Dragon?

Ok so recently i acquired a Chaos Emperor dragon-Envoy of the End. I have added him to my deck only used for friendly matches against my friends. Though i was thinking, I have a Decoy Dragon, and if my Chaos dragon was to be destroyed by its effect or due to battle, would decoy be able to bring him back also, does decoy dragons effect continue to activate as long as i have more than one 7 star dragon type monster in my graveyard or once per battle phase?