... only if you're already nearly max level, and probably don't need the piety.
Indeed; I had already killed everything else on the level and thought "what the hell" and worshipped Binlor in order get ENDISWAL and access the subdungeon. Vampire with BLUDTUPOWA is nice
, I will add. There is a true spellcasting monster in this guy waiting to come out, but he needs that glyph...
That said, I think I may
have a way to actually
abuse this, but I'll need to try to see if it's possible. Using the monster whistle, I can position a monster inside the Ying/Yang dungeon near the exit. I can then farm piety as I described in my original post, but rather than killing Ying/Yang to exit properly I instead use WEYTWUT on the monster I created near the exit in order leave. I can return later with WEYTWUT again in order to rack up 100 more piety, repeating until I've run out of boons completely. You will need BLUDTUPOWA to regenerate mana to both teleport in and out.
Of course, that takes a ridiculous amount of scumming (need ENDISWAL or Binlor, WEYTWUT, BLUDTUPOWA, and
the Ying/Yang subdungeon) but it would be worth it to finally get to put that worthless subdungeon to use. Plus the only deities that can gain piety from this process are Binlor, Dracul, and Jehora, so it's not like you're likely to have a wealth of conversion options to rack up obscene combos.