I see that you want to keep it less than 80$ but you reallu shoyld try to add Nykthos, Shrine to Nyx beacause it's so powerfull in devotion deck.

I would remove 4 Grisly Spectacle and add 3 Hero's Downfall and 1 Ultimate Price . Nykthos, Shrine to Nyx isn't that necessary. Removing it would low the cost of the deck. You need more low cost creatures too.

I have a similar deck and here's some advice that I have learned the "hard way". Nykthos, Shrine to Nyx is actually pretty worthless in a mono-black devotion deck. Most of your creatures and spells cost less than 4 mana, with the exception of Gary. The only time Nykthos is going to pay off is if your battlefield is loaded with creatures, and by then, you shouldn't need to be casting a bunch of things. Also, I know you said you wanted to keep it cheap, but mono-black devotion decks use Desecration Demon and Nightveil Specter for a reason. They are powerful and provide awesome devotion. Pharika's Cure is also great against aggro decks as it can remove smaller creatures without having to waste a removal spell. Plus you gain 2 life, which if you think about it, is 2 more cards from Underworld Connections .

Good deck. +1. Why not 3 or 4 Hero's Downfall? Because of its price?

@Andre, as soon as I can afford them I'll pick them up. I'm a little more willing to pick those up since they'll be legal for awhile longer.