When I doom blade a creature that is undying does it go to the graveyard before it comes back to the graveyard say if I had a card that gave me 3 life everytime a creature got sen to the graveyard would I get 3 life everytime I cast doom blade on an undyin creature
702.92a (http://imtgapp.com/forum/index.php?action=imtg;area=rule;number=702.92a): Undying is a triggered ability. "Undying" means "When this permanent is put into a graveyard from the battlefield, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it."
So yes, the permanent goes to the graveyard before returning with a +1 counter on it if it didn't have any.