Purist badge on VGT:
This has been, to date, the hardest badge to do (and I'm only missing one last badge which is probably impossible anyway). It was the first badge that had me scum. I gave the first couple of tries a shot regardless of the altar, but there's only so far you can go without resists / health boosts. JJ was a close call but in sharp contract to GG, his piety generation slows considerably once you're done with the courtyard (whereas GG picks up massively at high levels). I tried several other builds, and some got close (Tower 9 close even), but I could not beat Horatio with anything except this dude.
Now, saying it was scummy is a bit of an understatement. It took me at least 6-8 serious attempts (and at least 2-3 extra for each of those where the initial altar was not good) to actually win, because something always went wrong (the usual worst offenders were pre-explored Binlor floor, and/or very late First Strike floor). If nothing went wrong, I messed up something. It's a really specific setup, having to leave extra magic-using popcorn to get back to 50 in Taurog, and even more guys for Dracul, on top of all the monsters you anyway need to leave to wipe curses...
Now, even on the successful run, I only won by the skin of my teeth. I didn't get HALPMEH, Soul Orb or Martyr Wraps, but I did get Viper Ward and CYDSTEPP, so I was good to go. Reaching T10 was actually not so eventful, nothing really screwed me over, I actually had "no misfortune 3" instead of "grim malus", Mystera was pre-explored, etc., so it was not so tight. I had, what I felt was, a lot of resources going into the boss fight.
I got H down to cca. 1000 health, when I ran out of blood pools. So plan 'B' kicked in, and I took a shot of Blood Swell twice as I had two popcorn saved just for this occasion. This got H down to <500 health, which was 5 hits, but I had no more blood pools or monsters. I did have my death protection, and my first strike, and Yang's Sword, so I thought it's not impossible to win. I hit H and got a dodge! Cool! So I used up the DPs but he still had 11 health more than what I could hit him for with first strike, and I only had 5 mana (with zero blackspace remaining). I had about 30 piety. So I needed a plan 'C'... In the end I desecrated Mystera (I felt really bad about it - but I didn't want to do the math for JJ, so I went with the safe option), got a Blood Swell, and just slapped that evil fat goat once off health, and the second time via first strike.
"Thinker", just without the "ache".