It's Winchester vs. Winchester on tonight's Supernatural finale and we could not be more nervous about it.

Dean's (Jensen Ackles) continuing struggles with the Mark of Cain led him to make some pretty shocking decisions in last week's episode, killing an unarmed teenage boy from the (Franken)Stein family just because of father and uncles, not to mention ruthlessly beating the crap out of Castiel (Misha Collins) when the angel tried to talk some sense into him. Even though Sam (Jared Padalecki) was able to figure out a way to cure Dean's Mark of Cain thanks to a posthumous email from Charlie (Felicia Day), Dean made him promise not to do anything about it.

Will the younger Winchester stay true to his word? In a word: Nope. Of course not! These are the Winchesters we're talking about—they've gone to heaven, hell, purgatory and back for each other countless times. And when Sam goes back on his promise, Dean's temper is not going to be pretty. Uh oh.

We're terrified at what's about to go down on Supernatural, so we got executive producer Jeremy Carver to attempt to put our fears to rest and answer seven burning questions about the season 10 finale.