Mulligans
This deck aims to overwhelm the opponent with a series of big boards in the mid-game with demons, Bloodbloom, and Ectomancy.
Early game: Kobold Librarian is typically the best option on turn 1. Use Mortal Coil, Spirit Bomb, and Defile for defense. Void Analyst and Vulgar Homunculus are both good turn 2 plays. Combine Nethersoul Buster with Crystallizer (try to get to 15 health) and other damage-inducing cards/HP.
Mid-game: Play bigger demons like Hooked Reaver and Despicable Dreadlord. Use Skull of the Man'ari for slower games to get more value over time and hopefully cheat out Doomguard. Try to finish the opponent with the Bloodbloom and Ectomancy combo. Use Bloodreaver Gul'dan if necessary.
Utility: The Soularium is included for additional card draw, primarily when you are searching for a specific card to close out the game. Curse of Weakness can be useful for delaying the opponent, or for making advantageous trades. Lesser Amethyst Spellstone is included for further removal and healing. Hellfire can be used defensively or to finish the game.