Archmage's Guild

Whenever you cast a instant or sorcery
spell put a guild counter on Archmage's
Guild.
At the beginning of your upkeep if you
have 4 or more guild counters on
Archmage's Guild, sacrifice it, then search
your library or graveyard for a card named
Ehrin Heir of the Archmage, put it into your
hand then shuffle your library.