Mox Opal (223) [Modern Masters 2015] Legends Awakened where X is the number

where X is the number of Allies you control

{T}: Put a card exiled with this artifact into your graveyard

Set: Shadows over Innistrad Type: Enchantment Rarity: rare Cost: {1}{G} Creatures you control have "{T}: Add one mana of any color

Set: Revised Edition Type: Creature — Merfolk Rarity: rare Cost: {U}{U} Other Merfolk get +1/+1 and have islandwalk

Set: Wilds of Eldraine Type: Legendary Creature — Rat Noble Rarity: rare Cost: {2}{B} Whenever another Rat you control enters

Mox Opal (223) [Modern Masters 2015] Legends Awakened where X is the numberSet: 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.