@sitnaltax:
The "tough" part is mainly the scumming and a bit of luck comes into play. It's really amazing that the Rat can win even without Halpmeh and Soul Orb. It's really down to whether you can get some good items and conserving blackspace. The first time I won, I had Vampiric Blade and Platemail, that really makes it easy, could even win without dipping into Dracul. You just have to make use of lifestealing, a little like how Vampires use bloodcows, and sometimes just munch on popcorn to ding for the extra push, especially against the more troublesome foes or to make use of level up to wipe poison and mana-burn.
Halpmeh is obviously one of the best glyphs, but even Pisorf from Binlor or just Burndayraz are also good enough. As Tinker mentioned in her Rat post, Lemissi can help you access unreachable blackspace and can be super useful even if you leave it to the end for H. Weytwut could also work, to help with positioning of foes.
H is a joke for Rat, especially when you have Platemail. You really only need like a few 100 HP (really little) to corrode him and then he would go down super easily. So, really clearing the 9 floors before him is the main "challenge".
I am pretty sure you just need more practice, granted it's quite troublesome having to scum for first floor PM. And of course, some luck,

Good luck! Hope to see your full rainbows map soon,
