User blog comment:SethRollinsBabyFace/Who do you think It's Final Boss?/@comment-27879557-20160319194032/@comment-25707465-20160319201501

I'd think this one. It's the biggest, and the most difficult to access. Remina's will probably yield exposition about what really happened, and you'll have to go to the center of the world to fix it.

Kinda like in the original trilogy, in the end.