The natural inclusions in any deck playing Darcy are Mishras Bauble, Unholy Heath and, if paired with Blue, Expressive Iteration and Counterspells
As of right now, the venture/dungeon mechanic is parasitic
No, because thats the same as saying every player should be forced to endure chaos decks in casual EDH, because its fun
Heck, it can even help fix your mana (which is oh-so-important when you're splashing a third color to flash back Spider Spawning)
Possible Highlights
First of all, there is a lack of effective card advantage engines available to Dimir-colored control decks, which makes it hard to play control decks in the first place, but also makes it much more costly to be stuck with the Excruciator in hand, Secondly, it is not leveraging one of the best strengths of the Excruciator, which is that it presents multiple angles of attack