Mulligans
Aggro Mulligans
Against aggro decks you must need some early healing and clear.
Control Mulligans
Against control decks you can be greedy and keep the turn 6 combo Curse of Agony and Lady Darkvein
Classic OTK Warlock with Tamsin's Phylactery but in Classic OTK Warlock with Tamsin's Phylactery but in combo with the new legendary Lady Darkvein that ideally gives the deathrattle to cast Curse of Agony. If this combo can’t be played, you can rely on the Naval Mine.
Other cards are especially removals and situacional cards that could help like Steamcleaner, Smothering Starfish and Rustrot Viper.