The "Eldritch Onslaught" deck is a tricky mix of flashback spells and wily creatures. With your bewildering array of magic, you'll soon have your opponent spinning in circles.
With this deck, you want to fill your graveyard as soon as possible. Target yourself with Dream Twist, activate Deranged Assistant's ability even if you don't need the mana—even enchant yourself with Curse of the Bloody Tome. It may sound strange, but it will definitely help you win.
Your deck is filled instants and sorceries with flashback, which you can cast from your graveyard. Every time you put one into your graveyard, it's just like drawing another card you can cast! Cast twice as many spells as your opponent, and you're probably well on your way to victory.
Many spells in this deck keep your opponent's creatures off the battlefield either by damaging them or by putting them back in their owner's hand or library. Combined with your defensive creatures, you should be able to survive long enough to take control of the game. You might finish your opponent off with Sturmgeist or Charmbreaker Devils or use Burning Vengeance to dominate the late game.
After you have a good sense of the deck, there are multiple ways to personalize it. You can concentrate on the library-depletion plan, perhaps with Magic 2012 cards like Jace's Erasure. Twist the focus to your own library, and you can use the instant win condition of Laboratory Maniac. Beef up the flashback content of the deck with cards like Devil's Play, allowing you to deal as much damage as you can afford . . . twice!