*Everyone who chose a faction appears in a large white tiled room* Congratulations on only one death during that whole fiasco. But now time is seriously running out, so I'll give you all about an hour to stratagize. Please note that in this final battle, unlike previously, Codex aren't allowed regardless of the remaining members of a side. 
This little battle royal of each faction fighting all the others will take place in a dimension of my creation. A very large replica of the original planet. A pristine form of earth, equestria, and many other planets. 
The rules are quite simple. If you die, you're out. If you can no longer fight, you lose. If you leave the dimension for any period of time, no matter how small, you're locked out. When only the members of one faction remains in play, that faction wins. Good luck.