Forum:Homemade Dark Deck

I don't have many good cards, only some stuff I got in trades and things from Shonen Jump. I'm trying to put together a Dark deck, and came up with this. It works, but it's sort of awkward; it's simply not good enough. I've tested it against two different Six Samurai decks and a Gemini deck and it's basically on par with them.

My original goal for this deck was to build it around a Doomsday Horror/Rainbow Dark Dragon combo. I want to know about some cards that should go into this deck or cards that might work well; anything to make it better. I already know about the obvious like Mirror Force and other staples; I simply can't afford them. Feel free to mention non-stapled that are expensive, though. I 'm more interested in learning about new cards. I have two of the Earthbound Immortals, Cusillu and Ccapac Apu. Do you think one of them should go in? Thanks for any help.