Basic Schtick
Mind control their creature, use them to beat face, and then sacrifice them.
Card Review
The heart of this deck are the control cards: Mark of Mutiny, Traitorous Blood, and Unwilling Recruit. For 3 mana, each of these gives you control of the creature for the turn: the first two also give the creature a boost, so that you're staying ahead of the curve.
However, mind controlling the creature isn't cute enough: you need to do something with the creature once you have it. Plan A is to use Bazaar Trader on that creature: that card allows you to give permanent control of the mind controlled creature to a target player. (I would suggest targeting yourself.) Plan B is to sacrifice their creature to the Jinxed Idol, sending that present across the table. Plan C is to sacrifice the creature to a suspended Greater Gargadon (or, as it is known in this deck, "feeding Gargthulu").
The Mycosynth Wellspring and Ichor Wellspring provide card advantage and deck thinning. Play them as soon as you can, but hold off on feeding them to Gargthulu until you are running low on options or about to miss a land drop opportunity: you don't want burn the time counters on Gargthulu too quickly.
Fury Charm offers solid flexibility, and can work great as a combat stunt. It can also buy you some time if you aren't ready for Gorgthulu to drop.
Grim Lavamancer is for mid- and late-game spot removal of the little guys not worth mind-controlling. It also works for cleaning up your graveyard, which helps when facing Tarmogoyf.
Dominus of Fealty is a win condition: if you manage to drop this guy and they don't remove him immediately, you've pretty much won the game. Just let him be a 4/4 flying blocker and give you control of their permanent (ANY PERMANENT) during your upkeep. Then he can swing in for the kill...probably with one of their creatures in tow.
Jinxed Idol is another weird win condition. In addition to providing a particularly brutal way to sacrifice their mind controlled creature, Bazaar Trader
+
Jinxed Idol
allows you to keep passing it back. The amount of damage that Jinxed Idol will do should not be underestimated.
