Nightbane

[Dynatos]

You're going way crazy with the Heroic mode instances, Bolty. While the mobs DO hit hard, I've never had any mob (or even bosses in their enraged state) hit me for more than about 4,000 or so in a single hit (well, I've had Capacitus hit me for 5700 during his brief enrage.) Even on pulls where there's more than a couple of mobs to tank, I can usually secure enough aggro to keep a peel from occuring after the first heal. I haven't yet done Shattered Halls on Heroic (I've primarily been corraled for Mechanar and occasionally some Slave Pens), so maybe this is where you're seeing hits for 7500 (the gladiators, maybe?) I still think that you pulling aggro on the first heal is the tank's problem, not yours, however.

Heroic Blood Furnace. The 2-Felguard pulls near the end. Each Felguard hits for 8k. It's only doable with 1 healer if you have a Warlock, and even then it's tricky. Mathom (feral Druid), Midori, Kateley (Mages), Bevock (Paladin), and I, all strong players, did it without a Banish available. Mathom was being literally one-shotted by the 2 Felguards hitting him at once - Bevock (a holy Paladin) and myself (a holy Priest) had to heal spam like you wouldn't believe.