I usually just tell the group you pull it you tank it I am not pulling it from you since the healer cant pull apart from early healing (then I do get the mobs). I do random pugs and after the first mobs i decided how fast I go. If one gets impatient I usually say "mate you are doing the instance because i am the tank and tanks are hard to get so either play along of f off" usually makes the record straight and clean
just DG 1 mob dps will start burnin him instead rest of pack = win and u can proceedd with rot u use without worries :P
Well often I will Taunt, Deathgrip, Death & Decay.
But regardless too many DPS are impatient to kill stuff.
Even when I Deathgrip pull, before I even have a chance to do anything else, sometimes DPS are already blowing the world up around me.
One thing I hate about patches 3.3 and 3.2, are all the "overgeared" noobs that would never have gotten so geared in the first place.