Monday Magic - Black Devotion Template

At major Magic events over the last couple weekends, Master of Waves focused blue devotion decks have been blowing people away in Standard.  The success of these decks combined with my assumption that devotion will continue to be relevant throughout the remainder of the Theros block has inspired me to start testing devotion in some other (cheaper) colors.

On the table right now is a black devotion template.  Using only cards from Theros, I'm hoping this list can serve as the template for a block-constructed deck once the full block has been released.

As usual, I'm building this deck only from cards I actually own.  I'd like, for example, to run several copies of Hero's Downfall in place of Lash of the Whip for much cheaper, much more effective removal, but I only have one of the former.  I'd also like to run a couple copies of Insatiable Harpy to help deal with evasion and Whip of Erebos to recur my enters-the-battlefield devotion effects.  I'd also love to have a couple copies of Rescue from the Underworld for further ETB shenanigans; alas, I have none.

Here's the current list.  It's a little heavy on the upper end of the mana curve, but hopefully I can fill some of the gaps mentioned above and the next couple sets will provide a bit more for surviving the early game.

Creatures:
2 Abhorrent Overlord
3 Baleful Eidolon
4 Disciple of Phenax
4 Gray Merchant of Asphodel
1 Insatiable Harpy
2 Keepsake Gorgon
4 Mogis's Marauder
1 Nighthowler

Instants:
1 Hero's Downfall
3 Lash of the Whip
4 Pharika's Cure

Sorceries:
4 Read the Bones
3 Sip of Hemlock

Artifacts:
1 Whip of Erebos

Lands:
23 Swamp

At this point, the basic strategy is pretty straightforward: Build up my devotion by dropping permanents until I can hit Gray Merchant or Mogis's Marauder to deal tons of damage.  The Overlord is an alternate win condition, plus a sac outlet so I can recur the ETB effects if I can't win with some burst damage a bit earlier in the game.  Read the Bones helps control my draws and look for what I need, with Pharika's Cure offsetting the life cost.

To form a more effective baseline for future modifications, the changes I'm hoping to make within Theros are:

• Add more Hero's Downfall, removing Lash of the Whip
• Add another Whip of Erebos, probably removing a copy of Read the Bones
• Add another early-game creature or two, removing either Pharika's Cure or Nighthowler

I intend to play a few matches with this setup to see how it goes, with particular care going towards tweaking the overall speed (this may end up being too damn slow) and seeing whether Nighthowler and Insatiable Harpy are even useful.  Either way, I think this deck will be pretty fun to play, so here's hoping it's somewhat effective, too!