Sensei's Notebook

During your upkeep, put one Divine Counter on Sensei's Notebook.
{x}{t}: Exile target Artifact from a graveyard with a converted mana cost less then X. Then put a "Divine Counter" on Sensei's Notebook. X cannot be 0.
{x}{t}: Remove X "Divine Counters" from Sensei's Notebook. Then, you may cast an Artifact card from Exile with a converted mana cost less then or equal to X without paying its mana cost. X cannot be 0.