Dark Depths by itself is a threatening and imposing card, but theres a fun combo with Thespian's Stage where the copy technically doesnt come into play, so it already has no counters and immediately places the Marit Lage token into play
You can then tap them to take a face-down attacking creature and turn it face-up, completely skipping any cost that they might require
The deck has good ramp and solid sweepers, including Living Death, Their Name Is Death, and Mutilate
Black kills what matters, strips hands apart, and tutors exactly what it needs when the game tightens up
I dont know whether the combo is overhyped or not, but if its around to stay then this will likely remain one of the most desirable cards with this mechanic