The Dark Lens

The Dark Lens enters tapped.
Whenever a creature deals combat damage to you,
The Dark Lens becomes tapped, then that creature's controller gains control of The Dark Lens.

{t}: Choose half of your non-desert lands rounded
up, they become desert wastes and lose all other land types and abilities. Until end of turn whenever you set a value for X double it for each time The Dark Lens has been activated this game.