Originally Posted by Wrecking Crew
I thought it was a co-headliner tour, I saw somewhere that Zombie would close some nights and Slayer other nights.
This. It's a co-headliner and Slayer + Zombie alternate the closing spot. Regardless of where they play, it seems as the setlists are always the same. I'm positive Slayer's set has been the same 16 songs each show.