precognition is much better than sundial in this deck, upped sundials interfere with the automulligan, so i am assuming unupped sundials. you are trying to get in as much damage as possible before the opponent gets set up, sundial gives most decks a turn to accumulate quanta and cards.
Long Story short - Sundials do more harm to your damage than good. Precogs also allow you to see the opponents hand, too see if you need to wait a turn to pay silence.
