Mecha'Lock

You don't want any of the Mecha'Thun combo pieces in your hand as you won't use them till the very end of the game (except for 1 Plot Twist which you use after drawing with The Soularium). Aranasi Broodmother's heal on draw is very important as it keeps you alive, therefore you don't keep this card in starting hand. Twisting Nether and Lord Godfrey are too high cost of cards to use early on so it would be more efficient to mulligan these.