Yggdrasil, the One Tree

Yggdrasil can be your commander. If it is, you can play it from the command zone.
{t}: Shuffle your library, then reveal the top card. If it's a creature card with a lower converted mana cost than the number of lands you control, you may cast it without paying its mana cost. If you do, exile Yggdrasil.
Rooted in the river Dream and scraping the stars, none can escape the shadow of the World Tree.