While working on the Quest "Pride in the Name" in the Savannah, I was pulled into a phantom battle from which there was no escape.
When I first entered the cave, two horned monkey spiders pulled me into battle. After defeating them, Mizizi Redband talked to me. Because I was interacting with her I didn't get out of the way of the battle circle in time. Whatever mechanism pulls us into battle when we first enter activated and pulled me back into an empty battle circle.
The problem is, I had already defeated the spiders and they were gone! Because they weren't there, I couldn't 'finish' the battle. I was stuck in the circle with a battle half-started, still able to open my spell book and take a screen capture of the quest name, but unable to finish or escape in any way.
Porting out was not possible, neither was logging out. Fleeing was not possible because there was no real battle going on.
The only solution I could find was to close the game window manually and log back in ... which put me outside and forced to repeat the first battle with the monkey spiders again.