The Imovable Fortress

When The Imovable Fortress enters, choose target opponent. You get an amount of {e} (energy counters) equal to the number of nonbasic lands that player controls.
Whenever The Imovable Fortress attacks, you may pay {e}{e}{e}{e}. When you do, destroy target nonbasic land defending player controls, and creatures that player controls without flying can't block this turn.