Murder's at Karlov Manor was indeed a crosspromo set with Clue. But fans loved it, actually. It was yet another return to fan favorite (admittedly one of my favorite places too), Ravnica. Ravnica sells MTG, it was too easy. The added flavor of it all being canon to MTG's story helped sell it too.

Right but still. The storyline was clearly shoehorned in. (TCC made a video explaining why it sucks) 'Sides the set itself only had a handful of bombs, so no matter what you're losing money by buying sealed.