"It is returning through the dark. And then, Doctor? Oh, but then he will knock four times."

Doctor Who

As Foretold

At the beginning of your upkeep, put a time counter on As Foretold.
Once each turn, you may pay {0} rather than pay the mana cost for a spell you cast with mana value X or less, where X is the number of time counters on As Foretold.

Wilds of Eldraine: Enchanting Tales

Double Masters 2022

Amonkhet Remastered

At the beginning of your upkeep, put a time counter on As Foretold.
Once each turn, you may pay {0} rather than pay the mana cost for a spell you cast with converted mana cost X or less, where X is the number of time counters on As Foretold.