I've heard that Vampire on Vicious Steel was supposed to be brag-worthy:

To be honest, I won it on 1st try...

Now, because everyone said it would be super-hard, I did give a bit of thought to it before attempting it, and I specifically re-thought my potions policy in anticipation of what I expected the challenge to be.
So my reasoning was for strat:
Blahblah is a big vampire. He inflicts 120 points of magical damage, and has tons of health. So what seemed the right way to kill him was to be an even bigger vampire: deal&steal as much damage as he does. So resists in the 40%+ range, lots of Lifesteal, sufficient damage.
The Indomitable corrodes and is not much of a snack once he's down to 1HP. It seemed reasonable that if I combine exploration with fighting him, and uncover just enough (i.e. 2-3) tiles to keep him in 1-hit range, then I can steal back what he deals me. Knockback helps burn through DPs. So all I needed was blackspace to fight him, and basic endurance to get him down to 1 HP & pop the first couple of DPs.
So this translated into the preps:
Dragon Shield to bring resists.
Patches because it's mostly no-downside, and can reasonably give at least 1-2 shots of resists.
Elite Items to give a chance at scoring the Elven Boots (and/or Yendor, Keg of Health, etc.).
Translocation Scroll to pick up Elven Boots or Yendor.
Bear Mace for early de-clogging, faster DP popping and secret sub access. I thought about Shield but without the Blacksmith secret sub it's not enough to dominate The Indomitable so I went with the more reliable prep.
Mana Boosters because I don't really need fireball and because I <3 glyphs.
I brought in Reflex / Whuppaz (both to be used against BlahBlah) and Burn Salve and Fortitude. The idea was that Illusions make decent blood cows, except for their nasty habit of weakening. So if I have a ready solution to the weakenings, I can benefit from an additional monster type's health, and still clear it if it starts to become prohibitive (or in any case before fighting BlahBlah).
I figured I'd have at least 50% chance to score Elven Boots (got lucky and found it), which should make the rest of the map feasible. Ledger sub was worth blackspace +30CP, Monster Den gave me XP and curse wipes. Early WONAFYT helped preserve exploration for fighting The Indomitable (though I found him quite late nevertheless, somehow I explored in all directions except where he was...), as well as gave me valuable bits of bonus XP. Rest of glyphs were OK, nothing spectacular, I did cast CYDSTEPP a few times but I would have greatly preferred GETINDARE over it. I had massive amounts of blood pools / potions left in the end, so I think even without some of the lucky finds the run would've worked out.
I've read that the two hardest combinations are supposed to be Monk on VS and Vampire on VS, I haven't found them so tought, maybe I just got lucky. For me the hardest badges were Goat on Naga City and Vampire on Naga City (and I've far more experience playing Naga City than any other Vicious Dungeon, otherwise I find Naga City quite manageable and often PQI it, so it's not the map but rather the specific interaction with Goat and Vampire that I find difficult).
"Thinker", just without the "ache".