Ah, the wonderful-ness of PuGs! Yesterday's daily heroic was Shadow Labs, which isn't one of my favorite places even as a normal instance. A group was looking for a tank, and I said I'd go...
And ended up regretting the moment I saw their group makeup. A holy paladin (that was fine), a warlock, an elemental shaman, and a hunter... meaning that there would be one real CC (I tend to discount warlocks as CC, because it takes away from their DPS, and it's a bit sketchy of a CC, I've found) for the second boss' room. But... maybe. Just maybe, we could work it out.
We go in, and the first few pulls are all right (except, that I notice, that my health was going down and my health wasn't going up too much faster, so I pop into my full tank gear, with 1K more health and 7K (or so) more armor). We get to the pull with the warlock and his group of imps. I LoS pull like a good tank, and swipe and mangle away... and die. The rest of the group survives, and I get resurrected. I venture, at that point, the question of how much +healing our healer has. "1700" (and some change), he answered. Okay... we shouldn't have this issue. I sigh, but keep going.
Room of the first boss. All casters. Our hunter is beast master, and, apparently, has no idea how to trap. I get aggro on two out of my three mobs (the mobs I plan on off tanking), and run behind the wall... yet, somehow, my main target doesn't come to me. We could deal with that. Really. So I get better aggro on the other two with two hits, and then charge off to get skull, which was being attacked.
My rules for tanking are easy enough. Please wait until I get at least a mangle on small mobs, a mangle and a lacerate on a medium sized mob, and a mangle and two lacerates on a boss before you go, or I can't promise good enough aggro to keep it off of you. If you do manage to get aggro from the mobs I am tanking, I'll take pity on you twice and pull it off. Third time, you're out of luck and can tank it yourself. Good luck. (This rule, does not count if you decide to attack something that I am not main attacking (such as attacking star (the third kill in my killing order) when one should be on skull, and x is still up as well)).)
I watched the hunter... who didn't trap the trap, but killed it as the rest of the group were getting the main targets down. Twice this happened, and he mentioned that I should pull back father so he could LoS the target. I blink at him, and told him that he could LoS the mob that he is supposed to be trapping himself (not to mention that he could just run up and lay a trap at said mob's feet). The warlock wishes to seduce, so I let him... except that seduce keeps being dispelled, so he was fearing. Fine. Except... that both the square (trap) and diamond (warlock CC of some sort), kept dying before skull. Hrm... We got the three Felguard patrollers down without too many issues (except for him being attacked as I was pulling him back)...
I try again, now on the fourth pillar of the room. The hunter is standing ring next to the middle pillar on the first set of three pillars, so, theoretically, he could trap. Right? Wrong. He put the trap down and shot away. Didn't LoS. The diamond still went down first, and the square not that much longer after, and I was still tanking my skull and x. I raise the problem, and we do one more pull... and somehow wipe.
There was no way we could do the rest of the instance, much less the second boss' room, and I fake DC in pure frustration, and go off to play my mage...
Lesson learned: Best to do Heroic instances with guildies. It's okay if you'll die -- at least you'll have fun in the group.
And you can be sure that the person is competent (usually, anyway).