Nightmare Fuel / Convergence

• The mere premise is that Brainiac has collected forty to fifty cities from doomed worlds and has kept them in domes as part of some grand experiment. The people inside have no idea what is going on, their supplies are gradually dwindling away, and many are losing the will to live because they think there's nothing left for them in this cage. Then the domes come down, they find out they're on a completely different world, and now they have to fight for survival. Not fighting leads to destruction, fighting leads to destruction, they're screwed no matter what they do. And only one city will survive. Even worse, the planet they're on? It's sentient and it's making them kill each other.
• The fate of any dome that fails to win against another dome. Everyone and everything inside the domes is completely obliterated. The buildings crumble and the people break apart like they were made of stone, and all that's left is dust. Convergence: Speed Force #1 shows this firsthand when Wally West tries to help the people in the El Inferno dome, but can do nothing but watch as everyone dies.
• Lian Harper's resurrection at the hands of Dreamslayer in Convergence: Titans #1. He brings her back like it was nothing, and is ordering Arsenal to fight and kill Troia and Starfire or else he'll never get Lian back. Dreamslayer claims this isn't a hoax or a dream, and he actually has Lian by the neck while the poor girl is terrified and pleading for her dad to help.