This was a nice idea, but you get over the concept pretty quick. The Original mode was probably just about the right length of time before it just got boring... but you should make the unlimited mode a continuation from there. If I'm already releuctant to go on to get the 100k combo badge (the only reason I'm continuing to play), then I'm sure as hell gonna be reluctant to start again from scratch...
There needs to be a way to quit battles other than fleeing. I was doing Ss'lenck's Survival Arena and he ended up against 2 enemies that cast beserk on him, which meant he was doing flame attacks, which they absorbed, and they were doing flame attacks on him, which he absorbed. And there was no way out except to refresh the page.
It's too easy, I think. You've gone all about making it more complex, but it just seems to slow the game down, while not really requiring the same level of strategy as the previous ones. The fact that you never have to balance all 5 elements at the same time is one part of this, I think.
Great game, although I would have enjoyed if it had been longer and with a bit more variety, and I'm not having any issues with bugs or saved games either. 4.5/5