Mox Opal [Kaladesh Inventions] Guru Counter target spell if its

Counter target spell if its converted mana cost is X

"What separates us from mere beasts is the capacity for self-improvement

Set: Unglued Type: Artifact Rare Cost: {0} {T}: Roll a six-sided die

Set: Seventh Edition Type: Artifact Rare Cost: {4} At the beginning of your draw step

Mox Opal [Kaladesh Inventions] Guru Counter target spell if itsSet: Kaladesh Inventions Type: Legendary Artifact Mythic Cost: {0} Metalcraft {T}: Add one mana of any color. Activate this ability only if you control three or more artifacts. On loan from a private collection, this unique mechanism extracts power from a carefully prepared gemstone.