Strategy:

Once the terror of the meta, the classic Mech Mage still has its place and can earn you solid wins.  The deck is meant to be played aggressively, prioritizing tempo over value.  It matches up well against slower decks.  With a good curve, this deck is unstoppable.

The gameplan is to spam the board with mechs that have great synergy and go for the face.  Use spells or trade only if necessary to get rid of problematic minions.  It's important to get the opponent's health low enough before you run out of steam. 

Once the opponent's health is low enough, you have multiple win conditions - spells to the face, Antonidas' fireballs, an overwhelming board, etc.  Try to be strategic and tricky, as you have a lot of tools at your disposal.  Put down Loatheb right before a critical turn - e.g. you plan to kill the opponent next turn, or deny a mass board wipe.  You may want to save some low-cost spells (from Frostbolt, Tinkertown Technician, Clockwork Gnome) to power the Antonidas-Fireball engine.  Stealth on Antonidas is particularly powerful. 

Mulligan:

Mulligan for Mechwarper, Cogmaster, and Snowchugger.  Try to ensure a good curve by tossing out any 3+ cost cards, though you can keep Spider Tank if you have no other viable early minions.

Substitutes:

Aggro Substitutes: Replace Zilliax, Antonidas, and Dr. Boom with Fel Reaver, Fungalmancer, Leeroy Jenkins

Other Substitutes: Gorillabot A-3, Jeeves