Okay four five (but does that pend really count though?) quanta sources aren't going to get you anywhere. Even with Devourers, every other mono Darkness here has at least 8-10. And a Tower does not count as two pillars.
Manuel is right about the Parasite; remove that. Really, that shouldn't be used unupped really ever (although upgraded has only a few uses anyways).
Also, you don't have nearly enough damage. If you look at the mono Darkness deck that Manuel linked, you can see that it has 6 dragons.
Also remove the Earth Pendulum. It's useless. One card in 30 that is solely to burrow Devourers that could be used for more useful things isn't going to help. If you really want to utilize the Devourer's ability, then I'd suggest making a full out Earth/Darkness duo, not something like this.