Just managed to beat Zeromus tonight. Readjusting to the game after long periods of time spent away is really not much of an issue. I feel like I did a tight job designing my gambits, so whenever I come back I just let the characters do the work until I remember the ins and outs of how I had it all set up. I was itching to get back at Zeromus ever since that time I accidentally stumbled on him at like level 30 or whatever it was. 30 to 60 gaming hours later, I now enjoy my revenge.