Because Erebos, the Bleak-Hearted requires 5 black devotion to become a creature, I tried to construct permanents that utilize at least 2 devotion. Let’s talk about the 3 win cons which are all connected:

Draining means opponents will lose life and you will gain that much life. Gray Merchant of Asphodel is a strong example that plays off the devotion theme. You could easily have 10 black devotion where each opponent will lose 10 and you will gain 30 life! That’s all he does though, so you really want him to die to bring him back and repeat the drain… which connects to the sacrifice theme. Ayara, First of Locthwain allows you to sacrifice a creature for an activated draw ability, but then when Gray is played again she drains everyone for 1 herself.

Since Gray cost 5, this method is expensive. That’s why you’ll need to patiently get charge counters on the Black Market and have the Pitless Plunderer in play. The Crypt Ghast, Magus of the Coffers and Cobal Stronghold will together give you massive amounts of mana. Your pool is critical to continuing sacrifices.

And, the more you sacrifice, the more tokens you’ll create with Open the Graves and Ghoulcaller Gisa. You can sacrifice creatures at will with the Altar of Dementia and mill a target player. Use this as a response to a boardwipe. You’ll constantly need a victim to sacrifice for most of your triggers. The Dreadhorde Invasion gives you a free token to kill.

The Phyrexian Reclamation lets you bring back any creature to your hand at the cost of 2 mana and 2 life. Several powerful cards involve paying life. That sounds risky, but when you consider your creatures will likely have a drain trigger, you’ll more than make up for it… besides paying life fuels the Font of Agonies. If you’re really not getting the drain theme in your draws, you can keep paying life until you’re low enough to cast Repay in Kind and even the playing field.

And, since you have an indestructible commander, your boardwipes, In Garruk's Wake, Black Sun’s Zenith, and Toxic Deluge will be in your benefit - especially considering all the death triggers.

Then, if you can, instantly play Thrilling Encore after any boardwipe and you’ll have an awesome board state. Give them a taste of their own medicine!

Whip of Erebos is not as good as the Phyrexian Reclamation for returns, but the stupid lifelink means any amount of life paid will be made up for.

For super duper wins… the Dictate of Erebos is a game changer unless dealt with. And Bolas’s Citadel is very easy to activitate given how quickly you can create zombies, vampires, bats, goats, and drone tokens.

Unleash your inner monsters!