Mystical Tutor gives blue decks precise access to an instant or sorcery for one mana. It searches your library, reveals the selected card, and places it on top, making it useful for setting up a key turn or preparing an answer before your next draw.
A control deck can find Cyclonic Rift to address a developed board, while a spellslinger deck can search for the spell that keeps its engine moving. In a deck using Isochron Scepter, Mystical Tutor can locate Dramatic Reversal, providing access to the instant half of that setup. It cannot find Scepter itself, so the two pieces need different search tools.
Sensei’s Divining Top can move the selected card into your hand immediately through its tap-to-draw ability, with Top then going onto your library. A draw activation from The One Ring can also access the card without waiting for your draw step. Without that extra draw access, casting Tutor near the end of the turn before yours usually shortens the window in which opponents can disrupt the setup.
This is selection rather than a net gain in cards: the Tutor is spent, and you still need to draw the spell it finds. Revealing the target also tells opponents what to expect. Make sure you can pay for and legally cast the chosen spell when you need it, and avoid shuffling the library afterward unless you mean to abandon that top card. Mystical Tutor is strongest in decks with several instants and sorceries that solve distinct problems.
