Solo Tactician - Viconia DeVir - Gloomstalker (BG3 Act 3)
The battle with Viconia DeVir was quite interesting because the room was quite large with enemies spread out all over the place. It took some iterations to figure out the optimal routing. Over all, it was a really well designed combat encounter and Kudos to the design team.
Baldur's Gate 3 is an incredible game. Honor mode is the ultimate objective but before I tackle that I have decided to learn the ins and outs of the game by playing it on solo tactician mode concurrently with my main playthrough.