First off, this isn't an Overpowered/Underpowered thread. I don't think there's any problems with Decay itself. It's fills a niche in CB, and is targetted maily versus the 500AC near immortals.
The older brother to the VB in dealing with high AC.
Decay is both very powerful (allowing you to defeat much larger targets than usual) and quite weak (it can't actually kill), and it's often hard to find the right balance with.
It can be used to it's full potentially cheaply, working at maximum at base XP cost. But this allows it to be countered by AMF more easily.
My only gripe with Decay (and for note, I'm currently a Decay user) is that its prevalence, and ease of use for a relavtively negligable cost, typically shoe horns you into haveing to train AMF.
This is especially noticable on Single Minions, who don't have the luxury to try a PL backed 20 HP front minion (usually wearing an AoI, which has the strategic drawback of stopping you use AS on your Team), and it also therefore locks you out of using any other EO other than AMF.
As if you use EC or DM, there is no protection you can get to Decay.
Maybe we should have some other options to use, to stop the near requirement of training a 100K AMF, just to have the only protection to Decay.
Maybe we could add this to the little used ToE. Allowing it to give a physical resistance to a magical 'decaying' attack.
Is it time to break Decays near untouchable status?