Leonin Relic-Warder [Mirrodin Besieged] Basic Energy Metal Rarity: Uncommon Retreat cost:

Metal Rarity: Uncommon Retreat cost: 0

they must discard all copies of it

"Slifer the Sky Dragon" or "The Winged Dragon of Ra"

Set: Dragons of Tarkir Prerelease Promos Type: Creature — Dragon Rarity: Rare Cost: {4}{W}{U} Flying

while this card is on the field

Leonin Relic-Warder [Mirrodin Besieged] Basic Energy Metal Rarity: Uncommon Retreat cost:Set: Mirrodin Besieged Type: Creature Cat Cleric Rarity: Uncommon Cost: {W}{W} When Leonin Relic Warder enters the battlefield, you may exile target artifact or enchantment. When Leonin Relic Warder leaves the battlefield, return the exiled card to the battlefield under its owner's control.