When I was making this deck, it was meant to be just for fun but it turned out it's not that bad.
This deck is very good against Druids, not even you run Skulking Geist to remove those Jade Idols or Naturalizes but when you start putting in the Mechano-Eggs and Mechanical Whelps, they basically run out of their removal spells and die before they can do their combos and kill you.
The overall game plan for this deck is to control the board with Wild Pyromancer + Equality or Shrink Ray, play your Mechano-Eggs and Mechanical Whelps and try to magnetize them with SN1P-SN4P and Zilliax and if your opponent deals with them, you just bring them back with Kangor's Endless Army. This deck also runs a healing package to keep you alive.
Best cards to keep are Crystology, Flash of Light, Wild Pyromancer and Prismatic Lens. If you are facing aggro, always keep Righteous Protector, Consecration and Zilliax can be very useful, too. Against slower decks, also keep your clears like, Equality and Shrink Ray
Explanation of running these cards in the deck:
Crystology - drawing two cards for one mana is just great
Righteous Protector - amazing 1-drop against aggro decks
Crystalsmith Kangor - very useful to staying alive, especially against aggro decks, the double heal effect is too good
Flash of Light - keeping us alive but also draws a card
SN1P-SN4P - very good for magnetizing our mechs but can also be played as a tempo card on turn 3 against aggro decks
Prismatic Lens - drawing but it can also make our big minions cheap
Mechano-Egg - a mech that is very good when you manage to magnetize it
Zilliax - basically the best card in the game atm
Mechanical Whelp - a core mech of this deck
Skulking Geist - a card that makes short work of Jade and Mecha'Thun Druid
Kangor's Endless Army - bringing back your big mechs is just great
Nozari - Reno for 10 mana but without any restrictions for your deck, very useful to heal a massive amount of health in the late game
Shirvallah, the Tiger - since we run a lot of expensive spells, he will cost 0 mana by the time you draw it
I hope you found this guide helpful and have fun with this deck!