Hello, this is EXTREMELY EXTREMELY EXTREMELY hard to line up, however it is EXTREMELY game breaking(in terms of how you affect the way the arena is going) if you get it. I suggest reading the TL;DR'd version if you know how to play your class and understand the game.
Requirements: be a DK, be in an arena, have dark sim up. Be playing against rogue/mage/x team, or rogue/mage in 2s
I've only had this happen against mage teams, so the options can vary, however these are the possibilities, and the one we're going to aim for is getting his Ring of Frost:
Mage poms > use dark sim and if mage uses ring of frost, you steal ring
Mage poms > use dark sim, mage uses something else, you steal w.e he uses
Mage hard casts Ring of Frost > dark sim > steal it
Mage hard casts Ring of Frost > dark sim > he fake casts it and casts something else so you dont get ring
As you can see theres a ton of crap that can mess this up however if you DO get Ring of Frost, hold onto it as long as you can!
The exploit: If you get cc'd (in this case what worked for me was me being blinded), you can use Ring of Frost (instant cast) while blinded (im not sure about poly/other cc i havn't tested yet).
How is this an exploit/game breaking?: If you are cc'd that means the other team is going to be trying to land a kill, well guess what, you now have Ring of Frost and if you're lucky you can end up ringing all 3 people on their team as IT IS AN INSTANT CAST, and they can't do anything about it because you're in a blind anyway. It is NOT intended that you are able to cast and use abilities while blinded (cc'd in that matter).
The only line up that has happened to me was me stealing ring and being blinded, and using ring while blinded, I have not yet tried to see if i can steal poly for example and poly someone while feared. So who knows, maybe you can do more than what I did.
TL;DR:
"the exploit in short: dark sim ring of frost is useable while blinded."
which may also include other abilities while cc'd by other abilities.