Yeah, soul was a typo/standard item floating in brain since he is a devil. It's obviously the crown he wants, sorry.

You might not even have Laez in the party. Or you might not care what you think. Maybe she is also still on Vlaakith's side, too? If that is an option, I didn't try those dialogue options tbh.

Either way there are plenty of reasons not to be interested. What would be much better if we were to offer the same deal to Laez, if you don't take it. But even then he should have an alternate offer, for players who want to either stick with the Emperor or Gortash.