At one point in Brogue, I decided to run in a northwesterly direction (Shift+Num7). To my surprise, instead of running in that direction, the following message was delivered:
A dark presence surrounds you, whispering promises of stolen power. Succumb to demonic temptation? (y/n)
I've said No, to which,
The evil dissipates, hissing, from the air around you.
This was exceptionally unexpected, but it's also made me vastly curious. While I turned down the offer, I can bring it up again at any time by pressing the same key combination, to get the same promises and the same choice. This key choice isn't listed in the in-game help as far as I saw, so it's never quite explained what it does.
What happens if I do what appears to be selling my soul to demons? What is the benefits, the stolen power I receive? And what, naturally, is the catch, the drawback of doing so?