The most obvious answer here IMO is shame because backfire is a very well known skill and stealing nrg+interrupting a monk can be alot more disruptive than health loss. Cast it, wait two seconds, Diversion. Then, if the monk hasn't cast COP yet, drain their enchants so that they can't. This way, no matter what happens, things are win-win for you since if they cast COP immediately, it will get diversioned, and if they don't cast it soon afterward it no longer becomes an option because you will have drain the enchantment necessary for them to drop shame. They may COP, but with only one enchantment (watch to make sure they only have divine boon and MoR up) they will only remove one hex, diversion, which won't leave without doing its job anyway.

If they do cast an enchantment (or any ally targeting skill) immediately, shame will hit it and steal nrg from them as well as interrupt it. Play a glyph mes and glyph shame so you can do this twice in a row; coodinate it with an andrenaline spike for best results.