In Wizard101's release of Celestia there have been a lot of changes with the new spells and powers. Ice has new gear that rocks. Other schools have nuclear spells that are "off the chain", thankfully they are not chain-er :D But the unbalance dispel card finally was put out with the new update. This means that balance may likely not pwn everyone in 1v1 any more.
I've collected a lot of observations lately about arena. I think the school to watch now is life. I'll post more on that soon.
If you don't want to get nuked by a 2800 tough judgement I'd recommend unbalance for those tricky 1v1s. I probably won't carry them in 4v4 but who knows? Once I set up my deck for Ice I'll post it for comment.