This card recreate the Fel Stalker unit in Warcraft III has the Mana Burn ability that burn the enemy unit equal to their mana. Gameplay wise, it's a great card to pressure control deck by mid-range and aggro decks by forcing them to either take damage or play inefficiently.
Here's what I got, Lazy Peon is my favorite. Meat Wagon probably needs a different price or stats.
Why is Lazy Peon need the effect at all? This make it really weak compare to Dire Mole. Maybe as a 2/3 or 3/3 minion you can print this. Meat Wagon Catapult is the one I like most because it encourage Big Warrior.
I finally found some deck recipe that I'm happy with. They're going up. I'm especially concern about the second deck recipe has too many late-game cards and not enough Elementals to justify Cosmic Call. So, if anyone has any contribution, feel free to comment.