Destruction from the gods

{t}: Add {u/b}{b/g}, or {g/u}{u/b}
{t}{u}{p/g}{p/b}: Destroy target legendary land,
it's owner may lose 2 life and discard a card if
they do, then you search their library for a basic
land and a swamp.
When this thing leaves the battlefield, destroy or
take control of all basic lands your opponent
controls. they lose life equal to how many
lands were destroyed.