The biggest issue I see with this deck is that it only has 9 pendulums and the devourers for quanta. Even with your cards all being fairly cheap to play, I don't think you've got enough darkness quanta, but you probably have too much gravity quanta. You are very rarely going to have much quanta for drain life to be effective, for instance. I also think that the lone shard of void isn't going to help at all. Even if you get it right away, your other damage will still outstrip its effectiveness, and on its own it will not make any impact against healing stalls or anything like that.
One strategy you could try moving towards is a voodoo doll/acceleration deck, perhaps using gravity pull as well to either increase damage (gravity pull on a voodoo doll will make your opponent get hurt whenever their creatures attack the doll, and the acceleration's damage to the doll will also be dealt to the player, in addition to the attack increase, plus dolls have lots of hp) or to put on your opponent's creatures. It's only got 10 quanta sources, but half of them are pillars, so you'll get a lot more darkness quanta than you were getting, plus the gravity requirements have been eased by using less expensive cards. I'm still nervous about the low pillar/pend count, but I think it will still be an improvement over the original version.
Hover over cards for details, click for permalink
55t 55t 55t 562 562 562 562 5uk 5uk 5uk 5uk 5uk 5um 5um 5um 5um 5um 5um 5uo 5uo 5up 5up 5up 5uq 5uq 5ut 5ut 5ut 5ut 5ut 5ut 5v0 5v0 5v0 5v0 606 606 606 606 606 8plThis might not be the most effective way to make a darkness/gravity duo, but I think it preserves the theme you were aiming for, at least, and in that respect, I think that it's probably about the best you can do with a vampire + acceleration type deck. I'm a little nervous about the low number of quanta sources, still, but I did remove some of the higher cost cards, which conveniently were also some of the ones I felt were doing you the least good in the deck. The QI calculator actually says this is a perfect QI=5 on both types of quanta here.
I don't entirely trust the values that system gives for devourers, for reasons too complicated to get into, but this is partially compensated for by the fact that you (ideally, at least) won't have to play more than one of the dusk mantles or nightfalls, so the calculation is wrong in the other direction, as well.
Feel free to play around with the deck, though; don't take my word for it that it's better. If you think you see an improvement, try it, and see whether it works. Looking at other people's decks and ideas helps, but it will get you only so far; the best players are the ones who can make their own ideas work.
