Mox Opal [Modern Masters 2015] Goblin Artificer You may spend mana as

You may spend mana as though it were mana of any type to cast creature spells

Set: Judge Gift Cards 2004 Type: Creature — Elf Rarity: Rare Cost: {3}{G}{G} Echo {3}{G}{G} (At the beginning of your upkeep

Then that player loses all unspent mana and you add the mana lost this way

Set: Grand Prix Promos Type: Creature — Kor Artificer Rarity: Rare Cost: {1}{W} When Stoneforge Mystic enters the battlefield

Set: Judge Gift Cards 2009 Type: Land Rarity: Rare {T}

Mox Opal [Modern Masters 2015] Goblin Artificer You may spend mana asSet: Modern Masters 2015 Type: Legendary Artifact Rarity: Mythic Cost: {0} Metalcraft {T}: Add one mana of any color. Activate only if you control three or more artifacts. The suns of Mirrodin have shone upon perfection only once.