Mulligans
General Mulligans
The deck only contains a few spells, as such Hullbreaker is sure to draw at least 1 tome.
Together with Malchezaar's Imp or Hand of Gul'dan you can quickly refill your hand after using Tome Tampering.
Since Hullbreaker will deal a significant amount of damage to you, getting on board immediately after using Tome can be very benefitial. Boneweb Egg and Silverware Golem may help in this endeavour.
A first draft of what a Tome Tampering Warlock might look like. It is focussed on getting out an early Tome Tampering with some immediate follow-up draw options such as Malchezaar's Imp and Hand of Gul'dan.
The Augmented Elekk can shuffle double the amount of cards into your deck, these are likely more useful for the second Tome Tampering as you’ll have much more mana to spend on it.
The ultimate win condition is to either win on the board or to finish the opponent off with a N'Zoth, The Corruptor or Bloodreaver Gul'dan.