Mulligans
General Mulligans
I'm usually happy with any of these. They're good control early and they enable Auctioneer when you get him out.
Most people will expend all their removal when they see Fal'dorei Strider and Gadgetzan Auctioneer. At that point you drop the Dollmaster Dorian or if you already have Malygos in your hand, go for Kobold Illusionist. If it goes long enough you can even use Valeera the Hollow to get extra Sinister Strike if needed.