I was running a standard burning vengeance deck and I threw in an epic experiment, because I wanted to experiment how it would work in my deck. I payed the cost for epic experiment and three extra (so x=3). At the same time I played increasing vengeance. We weren't quite sure what to do. Should I have been able to exile a total of 6 cards?
We ended up exiling only 3 and the copy of epic experiment counted towards my burning vengeances. {Epic Experiment} {Increasing Vengeance}
If you copy an x spell on the stack, you copy whatever x is currently. So if x = 3, and you cast {Increasing Vengeance} targeting t, you do {Epic Experiment} twice in a row.
Note: Two spells cannot resolve at the same time. It is impossible to cast vengeance at the same time as epic. I am assuming you responded to epic with vengeance.
So to sum it all up: 2 epic experiments will be on the stack when you copy it. When all are done resolving, a total of 6 cards will have been exiled. They don't happen at the same time though.
Yes the two spells resolve separately. Exile 3, then anything with 3 or less CMC cast them. Then what u didn't cast goes to the graveyard. Rinse and repeat.
RESOLVED