Charging Beastmaster

Rush 4 - {g}{g} (You may cast this spell for it's rush cost, if you do exile the top four cards of your library.)
You may spend mana as if it was mana of any color to cast non-Human creature spells.
When Charging Beastmaster enters the battlefield, if it wasn't rushed you may search your library for a creature card, reveal it and put
it into your hand, then shuffle your library.