As long as this artifact is untapped, each spell that would cost less than three mana to cast costs three mana to cast. (Additional mana in the cost may be paid with any color of mana or colorless mana. For example, a spell that would cost {1}{B} to cast costs {2}{B} to cast instead.)

Trinisphere

Secret Lair Drop

Double Masters

"This exhibition of Nehra's Threshold Principle must be expropriated and examined for its potential applications in enforcement."
—Confiscation directive

Kaladesh Inventions

Designed to restrain petty thoughts, but used to repress entire empires.