It's in act 3.

Play it like I do: game ends with act 2, after that it's just a sandbox to try out spells. Act 3 is broken - and while it has been getting better, it is still nowhere close to the quality of act 1 and 2.

#JusticeForKarlach

Petition to save Karlach: https://www.change.org/p/justice-for-karlach