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.

"Sanguinius. It should have been him. He has the vision and strength to carry us to victory, and the wisdom to rule once victory is won."
—Warmaster Horus