Ben Ten, Ordinary Kid

Hero of many faces: If Ben Ten, Ordinary Kid is
your commander, choose a colour before the game starts, Ben Ten, Ordinary Kid is the chosen colour
{x} Dial Smash: Exile cards from the top of your library until you exile an Alien Hero creature,
Enchant Ben Ten, Ordinary Kid with that card,
it has vanishing X where X is the mana spent on
this ability