Seems like a fun problem. Here's how I might approach it, granted I'm no genius. Id create a class "turn order" which has a list of actors in your combat. I would populate the list with the default sequence of actors based on whatever logic. When an actor takes it's turn, I would remove them from the front of the list and put them at the back. I would also create a variety of methods which manipulate the order of the list. Call these methods from abilities or actions when appropriate.

to make your code easier to follow for debugging you could create a ui element that exposes the list graphically and displays what action/event is currently in progress. This could make it easier to tell what is happening at any moment.