Great Bridge of Joresh

Whenever a Bridge enters the battlefield, you
may draw a card. If you do, discard a card.
{w/b}: Create a very legendary 5/3 white and black
Human Warrior creature token named Defender
of the Bridge.
{g/u}: Tap and exert all lands you control. Create a
X/X green Treefolk creature token, where X is
the number of lands tapped this way.