This deck aims to disrupt your opponent's plan and then end the game with Blood Operative, Nightveil Predator from the sideboard, or building an instant board/insurmountable card advantage with Mnemonic Betrayal.
In current standard, black has the best removal but lacks a "game over" win condition like Carnage Tyrant or Niv-Mizzet, Parun. Doom Whisper is terrible accept against aggro. It turns out Mnemonic Betrayal is that win condition. You can reanimate your opponent's cheap threats if they're aggro, draw numerous cards and steal a drake if they're UR, or take some explore creature if they're GB.
Other key cards:
Seekers' Squire: I've found this to be a better Omenspeaker in the deck. Its chip damage is actually pretty useful and it draws a card more than usual because you have 25 lands and putting Blood Operative in the GY can equal drawing a card later. I've been super impressed with this card.
Blood Operative: This gives you incredible inevitability against control, stops phoenix and jumpstart cards, and provides some great lifelink.
Disinformation Campaign: This card is amazing against midrange and control. I've found 8 surveil cards is enough to keep triggering them given how much you churn through your deck.
Nightveil Predator: This card has been really strong against Jeskai, Izzet, and Golgari - which makes me wonder if it should be mainboard.
Unmoored Ego: Carnage Tyrant and Niv-Mizzet, Parun are both hard to deal with so this gives you a strong out.
