I've heard hearsay that some people have been discussing how they can gonna grief players on the PvE server when it comes out; I haven't actually tried to look for the discussion though
one of the primary ways to do this, other than by kiting people's mobs away from them so they evade bug or killing their mobs before they can tag em, is by polymorphing mobs that a player is trying to kill when they're almost dead
heres a few non-blizzlike change(s) I'll suggest to stop this, or at least make it only happen once per mob at the most which can be too much for some classes anyway; please pardon the redundancy
the diminishing returns on gnomish mind control cap, mind control, and polymorph (casted by players) and all of its variants last 10-20(undecided) times longer than diminishing returns usually do and apply to NPCs, and are shared between all of their variants if they aren't already, and as well gnomish mind control cap, mind control(used by players) and all variants of polymorph(used by players) share diminishing returns with eachother, so that mind control the mind control helmet and polymorph share diminishing returns with eachother
edit: now that I think about it I think it'd just be better to make polymorph wait 5 seconds before healing NPCs instead of that stuff
additionally, casting mind control and/or using the gnomish mind control cap twice in 40 seconds outside of instances will PvP flag you for at least 5 minutes
I'd prefer that any player caught doing this stuff with more than one cast to more than one single mob be either permabanned, or at least face a month ban+deletion of all characters associated with your account including on the PvP realm
If anyone has any other ideas I wouldn't mind hearing them; there is literally nothing you can do to stop polymorph griefers on a PvE server other than complaining to a GM, except maybe rolling 500k paladins and and rotating divine intervention on the mage every single second between all of them, and even then that only works on alliance characters