Hrimnir, really? He has always seemed like the easiest boss in T2 to me. Was the one my friends and I farmed before we could take on much else during delves.
haha this is an MMO, my friend. Since when is spending hours to acquire the gear necessary to defeat the content anything but expected? And try tweaking your strategies, contrary to popular belief, not every boss fight can be beaten the exact same way.
I've personally beaten most T2 dungeons without using any exploits or "cheesing" them...all except for Dread Vault, because I've never run it. Spider Temple last boss is the only super hard one, and once you gear up a bit and learn the fight she's not that bad.
Well they've all been beaten, so calling them "impossible" is a bit silly. Could be an issue of gear or your strategy. Just because your GS is high enough to enter the dungeon doesn't mean that you are really in good enough gear to complete it.