(Side note: for what purpose are you using this deck for? PvP? AI3? Halfbloods? Arena? Different playing environments require different strategies.)
It looks like your deck is too large, and lacks focus.
Drain Life works too slowly in this kind of deck and should probably be removed -- without Devourer support and/or playing mono-Darkness, you're not going to get enough
quanta to charge them up too well. The Empathic Bonds can go too, as they're also quite slow and you don't have enough creatures to take advantage of the healing.
For your supporting Life spell, you have two options: Adrenaline, or Mitosis. It's best to choose only one and focus on it.
If you choose Adrenaline (probably around 5 or 6 copies), then play with Minor Vampires and Nightfall (not Eclipse, as 3 attack is a sweet spot for Adrenaline). Consider adding Cloak as a way to protect your creatures from being killed.
If you choose Mitosis (probably around 4 or 5 copies), then add Devourers and Nightfall/Eclipse for the Devtosis combo (5-6 Devourers, 3 Vampires) -- play a Devourer and use Mitosis on it to make more copies and slow your opponent down. Once you have around 8 or so Devourers in play, start using Mitosis on Vampires for a win condition. If you choose to play with Mitosis, then using Empathic Bonds are a possibilty, but only because filling your board is possible.
The quanta base could probably be streamlined a bit more as well. Take a Life mark and work out a balance of Obsidian Pillars and Dark Pendulums -- that should smooth out your quanta generation.