Servan, Retiring Mentor

At the beginning of each upkeep, if no spells
were cast last turn, transform Servan.
{w}{u}{b}{r}{g}, Remove Servan from the game:
Choose up to two different legendary creatures
you own from anywhere with a total converted
mana costs equal to or less than the number of
experience counters you have, put them onto the
battlefield under your control. If Servan is your
commander, they gain partner and become
your commanders.