I did the same a few days ago and it was a whole lot of fun! Whenever I was riding on a bus, or waiting in a line...etc I would boot up dalaran heist on my phone and play some.
The most fun chapters for me were 4 (because some minions that are normally bad because of their stat lines can suddenly be good or even op) and 5 ( because those four last bosses consistently gave some of the most fun games ever )
The most op passive is definitely the robes. I NEVER lost a heroic run when I picked this passive ( there were some close calls though ) . I actually lost a couple of normal runs with it which is kind of funny but that's just how RNG works.
There were a lot of highlights but the most memorable one for me is the warlock deck with robes and double health passives , the +2 mana crystals anomaly , and a 0 mana Rin, the First Disciple that was always in the opening hand. 90% of games after I assembled this combo pretty much ended after a turn 5 Azari. I would have loved to play the ,,endless run,, mode that Blizz decided against implementing with this deck haha.