Snowball, The Concealed Energy

This card enters the battlefield with 10 {e}
(ten energy).
{e}: Draw a card, then destroy 1 land.
{e}{e}: Destroy up to 5 lands your opponent controls.
{e}{e}{e}{e}{e}: Exile the top 45 cards of your
opponents' library.
you can only activate this ability once.
When this creature runs out of energy, your
opponent gains control of it.