Deduce

Two cards for two mana, one now and one banked for later: that is the whole transaction, and its patience is the point. Straight card draw at this rate has always been a tension for blue, because a clean two-mana cantrip-plus-a-card would be a Standard staple that reads too well. Splitting the second card into a Clue is how the design pays for the rate. You draw immediately, then hold a permanent that owes you a card only after another two mana and a sacrifice, so the total investment to see both cards is four mana spread across turns. That deferral does real work: the Clue is an artifact sitting on the battlefield, which means it counts for anything that cares about artifact count or wants a token to sacrifice, and it converts flooded late-game mana into a card at instant speed. The instant timing on the front half matters too, letting it fill an end-step window or replace itself in response to a spell rather than committing a main-phase turn to card advantage. This is the Investigate mechanic doing exactly what it was built to do: hand a spell a delayed, flexible second half without the immediacy that would make it oppressive. What looks like a slow draw-two is really a draw-one that leaves a resource on the board, and the difference between those two things is where all the deckbuilding lives.