Mono-Black Removal Deck (Standard)

The Pharika's Cure's give removal of smaller creatures as well as I'm able to gain 2 life. The Hero's Downfall and Doom Blades allow me to remove larger creatures or smaller, please note in order to counter going against another black deck I have 4 Dark Betrayals in my side board. The Shadow Alley Denizens allow me to do immediate damage if my opponent has no creatures by the second turn or if they do and I can play a Rakdos Shred-Freak by turn two, assuming my opponent has no black creatures on the field I can do fast damage. Next I would hope to play either another Shred-Freak or a Deathcult Rogue to get more devotion. The Whips of Erebos allow me play a creature from the graveyard for a turn as well as it gains haste plus if a Denizen is on the field it will have intimidate, however I would use the whips' effect sparingly as it exiles the creature however if I'm putting in creatures from my opponent to the graveyard I should be fine. Then I play the Agent of the Fates and buff it with cards maybe even Pharika's Cure it if I can to remove more creatures. Erebos is a great creature to have out to stop my opponents from gaining any life as well as the whip combo allowing me to draw cards so long as I have the life and mana. The Gray Merchant of Asphodel is amazing in doing direct damage to my opponent and allowing me to gain that life. Then finally Abhorrent Overlord if he can come out gaining the 1/1 flying black harpies equal to my devotion to black and plus due to his effect on my next upkeep I have to sacrefice a creature, I can choose to buff up a nighthowler if it's out and I can spare a creature, Or I could sacrafice the Overlord then use the whip to bring him back and gain even more harpies plus he has haste this time depending on my devotion my opponent could be overwhelmed by the harpies while dealing with a large flying creature or a large nighthowler most likely bestowed upon something.