I mean, we knew about the whole sacrifice thing. I've dreaded this moment.. pretty sure I know what's going to happen.
Guts is supposed to be the sacrifice, but Griffith refuses.. and instead sacrifices the rest of the Hawks (including Casca) and thus begins Guts' hatred of Griffith.
Or they're all meant to be the sacrifice from the start, but somehow Griffith convinces the other demons (or manages to) to let only Guts live.
I'd love to be wrong.. :( I don't want Casca to die.