The fortress and starship of the Diviner, docked for years above the Tars Lamora prison colony, in which he hunts the Protostar and which ends as the ship that carries the freed prisoners home.
The Rev-12 is the vessel of the Diviner in the first season of Star Trek: Prodigy. It set down on the mining asteroid Tars Lamora when he began his search for the buried USS Protostar, and it serves as his citadel, supplying the colony's gravity and atmosphere. In flight it folds its outer sections into an armoured shell, and it is faster than the Protostar's ordinary warp drive.
When Dal and the others escape in the Protostar in 2383 with Gwyn aboard, the Diviner and Drednok give chase in the Rev-12, and it pursues them across the Delta Quadrant through episodes such as Terror Firma and Time Amok.
In A Moral Star the Diviner offers the ship to the prisoners in exchange for the Protostar, then cripples it. Rok-Tahk gets it running again, the crew use it to retake their ship, and it is left to the freed captives.