There are a lot of variations with The Demon Seed currently (and even some without). From full on Handlocks, through "draw through your deck asap", to even Zoo. Known Chinese contender XiaoT calls this one "broken". Some people have indeed been calling out Stealer of Souls as potentially becoming problematic in Standard as well. 

You know the game plan - once Blightborn Tamsin is in play, even your fatigue damage transfers towards your opponent. Hence Gadgetzan Auctioneer to speed things up.