Rhym, Solitary Hunter

First Strike, Haste
If there are no other creatures on the battlefield
you may cast Rhym, Solitary Hunter without
paying its mana cost. Rhym, Solitary Hunter may
be cast this way only if you control 5 or more
lands.
When Rhym, Solitary Hunter attacks alone, if
defending player controls no creatures it gets
+4/+0