Description	 Kill the shapeshifter, then go down the Easternmost staircase. The game then crashes.
Edit: It looks like floor 14 can't be accessed by any methods - I can't go down stairs, can't shaft into it, can't use wizard mode to shaft to 15 then go up stairs.
I want to complete the game with this character, so if it's an item or monster causing the crash I'd appreciate it if you could edit the save to remove it.
Why the hell was my account banned for adding this bug? Because I asked, as an afterthought, for my save to be edited?
I don't know what's going on with that account being deleted. I can't imagine any human doing it, so I expect it was some sort of automated system - maybe spam prevention gone wrong? I don't have any superpowers on Mantis so I can't put it back. If the user6518 account is important to you (I mention this because the name suggests it might not be), I suggest following up with a Mantis admin, maybe by filing a Mantis bug?
As to your actual bug report: that's a cool one. It turns out that the water nymph had temporarily transformed both the Vaults entrance and the up-stair on D:14 to shallow water, causing a sanity check when level loading to fail. I've fixed that sanity check to account for the possibility of temporary terrain changes, in https://github.com/crawl/crawl/commit/cea5463b436e. [^] If you update to a version at least as new as that, your save will continue working as normal, with no need to fix the save.