i didn't really have any problems untill round 3. the problem is that rounds one and two dealt with illustration, while the poster in round 3 falls under graphic design. This effectively cut off all artist who cant do graphic design.
round 1) It sounded cool, but the winners were chosen with the wrong standards: Everyone thought that the winner would be the best model, not the best representation.
round 2) LNR got a pretty difficult assignment, and that surely was a reason why few people participated. And once again won the best looking even if in some of them I couldn't even find any clue of the "plan".
round 3) that was just boring for the LNR, while SE always got better assignments.
Overall) I think you lost it. The idea of two forces one against each other is cool, while two of the working together against one enemy is boring. First of all: changelings are "love-powered", so in case of open war they lose. That's pretty easy to understand. I bet if you are going to ask for a battle, changelings will loose in a few hours. So the last round was the worst error: you made the whole "civil war" thing die, and also chose a tactic that a single enemy like the changelings would never adopt.
If you are going to make a new contest like this one, please consider this improvements:
-more judges voting, from mods from both the groups
-specify the vote criteria, and try to base it on creativity and not on the final visual effect. Consider that if I make a beautiful drawing for a contest but the assignment was slightly different I get discarded, and this didn't happen here. They did even win!
-try thinking more on what the assignments could be: the last one didn't even make sense...
And for the last round, consider that in a civil war if the leader is struck down, there is always a second one that will replace him. That's because only empires and tyrannies die with the death of the head, not the republics. Please, think about it: if you are fighting against your brothers just to end monarchy, you are not caring about who's organizing everything, you just want monarchy to stop.
DO NOT think that a population would reunite just because a part of them has been tricked, that's childish.
I think that in the first round, the judges had wrong the criteria when it came to deciding a winner. Second round, everyone on Luna's side were told that the were suckers and the assignment were uninteresting. And in the third round the other group gots a much better assignment than the other.
I think the whole idea of a princess based pony war had so much potential and it was all waste on this contest. Were shading wins over creativity and one group gets special treatment.