Change the text of target permanent by replacing all instances of one color word with another or one basic land type with another. (For example, you may change "nonblack creature" to "nongreen creature" or "forestwalk" to "islandwalk." This effect lasts indefinitely.)
Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.
The thunder of its hooves beats dreams into despair.
"It has been my honor to improve on the Thran's original design. Perhaps history will remember me in some small part for my work."
—Urza, in his apprenticeship