If going against aggro, make sure to mulligan Spirit Jailer, Soul Shear, School Spirits, Fire Breather. Void Drinker is necessary mid game to slow down aggro. Soul fragments will help you to survive a bit longer.
Early game is pretty much playing cards with soul fragment activation. (drop spirit jailer; play soul shear/school spirits/fire breather when facing early game minion threats to clear board) Enlarging cards in hand to complete the quest is a major priority. Play Void drinker for defensive measure against aggros. When you accumulate large number of cards in hand play plot twist for faster quest completion. The idea is to complete the quest to draw the highest card to hero power them to “0” cost (example: tickatus/cascading disaster) for easier access to corrupt them. If you are facing higher minion threats. Combo with headmaster ke’lthuzad+cascading disaster to steal their valuable minions.) Soulciologist malicia is also best to trade against threats on board + drawing Keli’dan the breaker can clear the board in an instant. Fel Lord Betrug+plot twist is best to play late game to trade against minions on board. When you draw Sathrovarr as “0” cost power, it can be beneficial in many ways such as using it to recover Tickatus/Y’shaarj the defiler to exhaust opponents deck. To dominate late game is to complete C’thun, The Shattered + you can also benefit ultimately from this by drawing it as “0” cost card + Sathrovarr to have many C’thun duplicates for ultimate destruction.