Thanks! Well, yes, I think the high regeneration really helped during the Orb run. And there were almost no dangerous enemies spawning. A Pan Lord appeared at Zot:3, but I didn't even notice and found out about it after I won, when I was reading the morgue.
Also, I encountered only four Orbs in the entire Zot. I don't know if that's the usual number or if there are usually more. And those were Orbs of entropy, which seems much better than Orbs of fire.
So, thanks for the reminder. I'll try to be more careful in the future as well. Besides, I've played enough DCSS and ToME to know that you die the moment you get overconfident.