ToME: the Tales of Maj'Eyal

I completed the corruptor quest, but also betrayed him after killing the anti-magic target.
Unfortunately I'm still unable to get corrupted shell. My game feels a bit gimped at this stage.
If this is intentional then perhaps the description should clearer.
Thanks!

It's intentional that you can't get Corrupted Shell if you've killed the Grand Corruptor.

By the way, you've posted this in the T-Engine 4 bugs forum, but I think this isn't an engine bug report and instead it's a ToME 4 bug report (i.e. it's specific to the game, not a problem with the engine that could affect other games using T-Engine). For future reference, the ToME 4 bug report forum is here: viewforum.php?f=70