Hearthpwn

Mulligans:

Against aggro aim for Defile, Hellfire, Demonwrath and Mistress of Mixtures.

Against Control and Midrange aim for Kobold Librarian, Undertaker, Mistress of Mixtures and any egg.

Strategy:

Get Undertaker out to get buffed by playing eggs, gain cards from Warlock's HP and crack the eggs with Void Terror, Sanguine Reveler, etc.

Each egg cracker has it's own purpose, Void Terror is for cracking Devilsaur Eggs since they have the most egg Health, Grim Rally for Scarab Egg to crack the egg and summon 3 2/2 beasts, Sanguine Reveler, Ravenous Pterrordax, Dark Possession, and Dark Pact for Nerubian Egg.

Power Overwhelming is for when you've had an egg for a turn so you can PO it, make a trade and if the trade didn't kill it it would automatically crack the egg at the end of turn.

Grim Rally can also be used for small tokens like the imps from Fiendish Circle and Scarabs from Scarab Egg.

Mistress of Mixtures is just for the 2/2 on turn 1 and health.

Spellstone is an excellent removal once you've upgraded it atleast once, and a great (and perhaps warlock's strongest seconded by Bloodreaver) source of healing.

Hellfire, Demonwrath and Defile is against aggro and occasional egg cracking.