Walking Ballista [Aether Revolt Prerelease Promos] 220 where X is the exiled

where X is the exiled card's mana value

Whenever an opponent sacrifices a nontoken permanent

Set: The Lost Millennium Card type: Fusion/Effect Monster Rarity: Ultimate Rare Attack: 2100 Defense: 1200 Elemental Hero Avian' + 'Elemental Hero Burstinatrix' This monster cannot be Special Summoned except by Fusion Summon

Your opponent randomly selects and discards 1 card from his/her hand and then selects and discards another card from his/her hand

or triggered ability

Walking Ballista [Aether Revolt Prerelease Promos] 220 where X is the exiledSet: Aether Revolt Prerelease Promos Type: Artifact Creature Construct Rarity: Rare Cost: {X}{X} Walking Ballista enters the battlefield with X +1 +1 counters on it. {4}: Put a +1 +1 counter on Walking Ballista. Remove a +1 +1 counter from Walking Ballista: It deals 1 damage to any target.