Cast Beacon of Tomorrows by paying ({6} magic symbol) ({U} magic symbol) ({U} magic symbol) , causing you to take an extra turn after this one and shuffle Beacon of Tomorrows into your library.
Declare Zethi as an attacker.
Zethi's second ability triggers, creating a copy of Mystical Tutor and causing you to pay ({U} magic symbol) to cast it.
Resolve the copy of Mystical Tutor, causing you to search your library for Beacon of Tomorrows and put it on top of your library.
Move to your extra turn, causing you to draw Beacon of Tomorrows during your draw step.