hey,
found it by accident and its quite simple but funnyprobably only works for opponent-melee classes like dk warri rogue pala etc.
when queuing for ashran, many ppl are waiting next to the dummies/ the border to enter ashran pvp. many ppl are dueling there aswell, all you need to do is duel with someone, let them waste their insignia/bubble/whatever saves them from your Mind amplification dish, mind control them and attack the Tanking dummy with a ranged attackthey die almost instantly if they go melee on it
maybe works too for non engineering players, if you kite them near the tanking dummy and your opponent will probably use some kind of aoe/semi aoe attack and accidentally hit the dummy.
I dont know about priest MC mechanics cuz I've never played it. maybe worth a try too.