Am I just comparatively bad at leveraging the abilities of other items, or is the Orb of Zot as crazy powerful as it feels for a prep? Your ability to instantly begin spiking high level enemies goes through the roof when even your thieves can whittle down their HP before fully engaging. Bosses require far less resources saved to defeat, to say nothing of what a Can of Whupaz will do to them. It's not even like you're trading in much statistical power for it, since prepping it still lets you spend gold freely in the dungeon shops.
It may not be very applicable to Gaan-Telet or probably the vicious dungeons which I haven't tried yet shame shame shame, but if I can cakewalk over the Slime Pits with a monk mostly using BURNDAYRAZ, there's probably no 'hard' dungeons that it can't wreck.
It's okay if you're saving up for and buying it during a dungeon run, or even just occasionally getting lucky and filching it via seal, but maybe it shouldn't be lockerable?