Form of the Snake

Hexproof.
When Form of the Snake enters the battlefield your life total becomes equal to the number of cards in your hand.
{2}{u}: Draw a card, then discard a card.
{2}{g}: Destroy target artifact or enchantment.
{2}{b}: At the beginning of your opponents next upkeep add five mana of any one color to your mana pool, until end of turn that mana doesn't empty from your mana pool as phases end.