Fel Guard's ability is kind of poorly thought out. Charge is pointless after the turn the minion is played, so you have to either play Fel Guard and immediately play another card to trigger it (6 Mana cards are notoriously hard to combo) or put him down right before you trigger an AOE blast (Unstable Ghoul, Abomination, Flame Trap, or Explosive Sheep). Otherwise, it's a 6/4 for 6.
Also, Soulfire + Sense Demons + 2 Spell Damage = Curse of Fel. Seriously. Even the mana costs.
Otherwise, there's some interesting stuff in here.