From the Vault: Exiled — Mythic
As long as Trinisphere 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 to cast costs to cast instead.)
Designed to restrain petty thoughts, but used to repress entire empires.