The two most important cards in this deck are Spider Bomb, Mechanical Whelp and Devilsaur Egg. The first one kills enemy minions, while the other two put some serious threats on board.
All these minions have deathrattles that can be triggered multiple times using cards like Play Dead, Fireworks Tech, and Terrorscale Stalker. Corpse Widow will help you cast your deathrattle cards for much cheaper.
The rest of the mechs are there to support these cards with the help of Magnetic mechanic. Also, as a Hunter you should never forget to use your hero power, and with the help of Clockwork Automaton you will be able to deal not 2 but 4 points of damage each turn.