The idea of this deck is to play the tempo/aggro style. It plays a bit like zoo.

Card by Card:

Mecharoo - Good mulligan card and a card to through out before a magnetizing play.

Northshire - The best card in the mulligan, a great target for a turn 2 Extra Arms

Power Word: Shield - Card draw and minion buff, great with Test Subject for a redo later

Skaterbot - Create tempo card, can turn any mech into a great Vivid Nightmare target

Test Subject - A create card to create value with the buffs in this deck (Extra Arms on turn 2 is notably powerful)

Dead Ringer - Draws many of the deathrattles in this deck. Can be a base for magnetic or Shadowy Figure

Divine Hymn - some secondary healing as well as a boost to a Vivid Nightmare'd minion

EVIL Conscriptor - Good Zoo style minion. The lackeys are powerful.

Extra Arms - The reason for this deck. Powerful tempo card. Can also be great for value with some of the enablers (Test Subject/Zerek)

Shadowy Figure - Can copy some great deathrattles as well as magnetized mechs. Also gains potential bonuses like rush, lifesteal and other text. Can be used to duplicate and active Zerek.

Shadow Word: Death - Important against early giants

Sn1p Sn4p - Another reason for the deck. Powerful as magnetized and solo, great target for the duplication effects as well.

Vivid Nightmare - Powerful card which can be used to create card draw, tempo and value (one of the allstars of the deck). Notably combos with Zerek.

Cult Master - Great Card draw in a deck that generates a lot of tokens

Mass Dispel - Tech choice against other Zoo like decks (Mech Pally, Mech Hunter) and works as draw vs control.

Replicating Menace - One of the main token generators and magnetic cards

Wargear - Another big magnetic card

Zilliax - The most powerful magnetic card

Zerek , Master Cloner - The value finally

Bwonsamdi, the Death - Deck thinning card draw. Notably can help find the Northshires to continue the draw.

Mulligans and General Strategy

Aggro matchup - Hard mulligan for a curve. 1 drop into Extra Arms is the best bet. Steer clear of Skaterbot on turn 1 though

Midrange matchup - Mainly Mech decks, consider keeping a copy of Mass Dispel especially if you have an OK curve.

Control matchup - Zerek and the Test Subject are the most important cards.

Please note the powerful synergy between Divine Hymn and Vivid Nightmare, as well as between Rush and Vivid Nightmare. Vivid Nightmare can allow you to quickly duplicate buffs on the Test subject and combos with Zerek in one turn. If you are playing a lot of control Seance is a good card to include instead of Cult Master.