Horntail's Arms

You'd all get mass sed and unless you keep yourself potted or have tons of hp, you'll probably die eventually from rocks or other attacks. What if you get sed, 1/1, and boom dead. Bishop wont' be able to heal cause it'll be sed too. Even then, bishop would probably die from rocks/other attacks.

Again with just regular sed, you'll need to take into account the person getting sed. What if they die? Will you give them heal? What about spawn?

I don't see a 1 party run, or even less, very plausible even if the 6 people were specially made characters, had godly gear, etc.

Well for one we avoid mass sed by not getting the arms to 50% hp until the end. That is quite easy to deal with. I can easily handle sed once there is only arms left anyway. Also a well experience party of 6 people could actually do this. Ideally I'd take myself, drk, pirate, bishop, shad, and another bishop likely. If all have very good survival skills the run is just a matter of time and patience for the most part. I hardly die at horntail honestly. If the party was reliable like that then the run would not so impossible as you say. I think it would be fun and challenging.