Asar, Fearful Physician

Lifelink
When Asar, Fearful Physician enters the battlefield, you may create Penny, a legendary 0/1 Quill artifact creature token with shroud and "At the beginning of your upkeep, put an ink counter on Penny".
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 ink counters on creatures you control.