Alright, a list of the dumb things I did on my best character so far, probably capable of ascending had I not dun goofed.
I put a wand of cancellation in my bag of holding, destroying a lot of my stuff, including a bunch of potions/scrolls/wands/etc. Thankfully the cancellation was pretty high in the list so I didn't kill a huge bunch of my wands, and I still had a passable supply left.
I was sacrificing for Grayswandir and accidentally sacrificed a dwarf at an altar with a priest, pissing off the priest and Tyr, and turning the altar chaotic.
I somehow burnt through the ice bridge in Medusa's lair, fell in, climbed out, walked back in, and still managed to climb out, blanking all of my potions and scrolls.
Despite all this, I got Grayswandir, cleared out the castle, and got my wand of wishing. I wished for what I still needed armorwise and used the wrested charge to get a blessed magic marker. I took those blanked scrolls I mentioned and made them into enchant armor and weapon scrolls and used tripe rations with them to fix all my stuff. By the end of it my AC was -25 so I was regenerating health faster than the enemies could hurt me. I was also dual-wielding +5 grayswandir and a +2 blessed silver saber. I was basically ready, and started heading down to tackle Gehennom, hopefully finding another magic marker so I could bring my second saber up to snuff and really kick some ass.
One problem: I forgot candles. I decided to head back up and grab them, bought seven, started going back down. Fought a frost giant, he dropped a pink potion. I had identified most potions at that point so I thought there couldn't be anything bad. It was a potion of polymorph, and next think I knew I'd lost my +5 cloak of displacement and my +5 hawaiian shirt, and was now a dragon. I was pretty pissed, but decided I'd just deal with it when I found that magic marker and maybe a lamp or wand of wishing. Anyway, orb of fate tells me something's coming, it was a 1 on the warning scale so I just walked up and smacked it down as soon as it turned the corner.
It was a cockatrice.
Son of a bitch.