Soloed Ironclad Cleaver (Attohwa's iron giant). :D Someone had zoned it to #01, beats me why they did it, but I decided I'd try and take it back home. It was so easy to kite, that I figured that hey, why not try and kill it? After some false starts ("stop @#$%ing en-stunning and en-amnesia'ing every predator claws!"), I settled for Levi (immunity to amnesia) and spinning dive, because magical pacts weren't doing so great. In total it took around 40 mins pre-rage (it must've not reset since it had been dragged all the way over to #01 since it raged so soon) and 50 mins post-rage to kill it.
It was reasonably easy pre-rage, Levi held hate well even with throwing some bio 2s at it, spinning dives were doing 900-2000 (with razing ruins atma) and it paths horribly around that hill where pulse martello is. Somewhat more problematic to kite when there's Bastion going on since I didn't want to MPK people with it. I think there might be a pinspot on that hill, because at one point it was making a huge detour, and then when I moved a bit it turned around and headed back the same way, but I didn't look into it much since I wanted to be far away to resummon.
Post-rage it got ugly. Levi's accuracy went through the floor, I'd often have to kite a good 5 minutes around the hill that he could hit even once and establish enough hate for spinning dive, and giant's hits started doing 300-500 normal, 800+ critical on levi.
I think it'd be a cake with 2 or 3 summoners. ^_^