Nightmare
Creature — Nightmare Horse
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.
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Illustrated by
Magic 2015#276RareEnglishLegality
Rulings
Apr 1, 2008
If you control 0 swamps, then the Nightmare has 0 toughness and will be put into its owner’s graveyard as a state-based action right before the next player gains priority.
Oct 1, 2009
Nightmare’s power and toughness changes as the number of Swamps you control changes.
Jul 1, 2013
The ability that defines Nightmare’s power and toughness works everywhere, not just on the battlefield.
Jul 1, 2013
Nightmare’s ability counts all lands you control with the subtype Swamp, not just ones named Swamp.