General M, Hero Summoner

When General M, Summoner of Heroes enters
the battlefield, return all Heroes in your
graveyard and in your exile zone to the battlefield.
Whenever a Hero you control dies, shuffle it back
into your library.
{w}{u}{b}{r}{g}: Search your library for a
Hero creature card, put it into your hand, then
shuffle your library.
"Heroes of times long gone! Come back from the
Realm of all things lost -and aid us one last time!"