Bruvac the Grandiloquent Bruvac the Grandiloquent is here to make all of your other mill cards even better
Adric, Mathematical Genius Adric, Mathematical Genius is another Doctor Who commander that would benefit from Lithoform Engine in the build because both cards copy triggered or activated abilities of your permanent
Whenever a permanent you control becomes the target of a spell or ability an opponent controls, you may draw a card
Unlike Obeka, Brute Chronologist and Sundial of the Infinite that protect our Slivers during our turn, it protects Slivers on our opponents turn, as after attacking they phase out at end of combat (that is before the beginning of our next end step, thus we are keeping all the tokens)
2 PACK MINIMUM
Personally, I lean more towards the two Tomes as being the most useful for most decks, while Book and Mine are both situationally better.