Ran into a rather intereresting infinite battle scenario with Nefarious Five fight (least I was amused, my teammates were getting very frustrated but I am an old has been raider from other games...)
We agreed ahead of time who was going to take the potion but at the last minute another decided they wanted the badge and it became a race to the potion. The designated person (swashbuckler) took the potion but forgot to remove gear in their haste. So we had an armed to the teeth swashbuckler turncoat who was extremely hard to hit.
We took out others of the nefarious five and finally got our team mate to take a nap when the nefarious privateer cast a group heal and woke her up. So it was down to the privateer and the possessed swashbuckler and the only one left of the team standing was our buccaneer. After many rounds of charms and more summoned minons the privateer finally went down leaving only a summoned minotuar standing. Who didn't last against the possessed swashbuckler. At that point it became endless turns where nobody could do anything and the enemy had no target.
For the sake of science I fled to see if it might be possible to return. I can confirm that isn't possible. Eventually everyone fled as the endless loop kept going and going like an energizer bunny. Is it supposed to do that?