Mafia 20. Radioactive Dreams.

I agree that some of the clues were difficult. But some were quite solvable. You just needed to spend a little more time on them. After the 3rd night, people weren't paying much attention to the clues anymore... Except for the one about Medja, and out of joy that they had solved it, everyone focused on him, even though Neyra had written that the murder was committed by Nabl.

Added 5 minutes later
The code is simple. It's the 2nd link in the request.

Regarding Tengro. Yes, there was a hint. They flew away together with the phoenix.

A succubus is often described as a young, attractive woman, but with clawed feet and, sometimes, webbed wings.

Added 1 minute later
And most images of succubi also have wings.