[quote=@Ryonara]
As for ways to end battles, how about a more definitive win condition? Like either scoring an objective or a TPK against the enemy groups. If Bastion is the goal, than whoever has her and escapes would "Win" the battle. Alternatively, whoever can eliminate the others first. 
[/quote]

Capturing Bastion first or killing each other off first were always options to winning the battle. The 3 post limit was more of a technical aspect than a story one. But certainly, whoever gets Bastion away from the Elicitor or kills the other side completely wins. The 3 post limit just ensured that process didn't take forever.