Shadow in the Warp is an insane card, even outside of this deck
At 8 mana and with such heavy black requirements he is rarely cast instead preferring to be cheated into play but with cards like Dark Ritual and Lake of the Dead and 8 mana card is at its second most realistic for being cast in black
This metric works well as a blanket, but it's still difficult to take a given card in a typical Commander night and distinguish between a really good synergy and a Game Changer
Losing access to green means you wouldnt get to play a beautiful foil Cartographer or any of the other green explorers, but if thats not a dealbreaker, Ive put a rough list together for this build over on Archidekt
A 6/6 for 6 mana is pretty standard, but it also gives you an immediate buff to one of your other creatures
In regards to building it, I want to give a shoutout to my friend Robert Stanley who helped me in playtesting as well as Stephen Dykman, who helped me figure out the best build despite not choosing to play the deck over the weekend