Aretopolis is a common Plane — Kephalai card from Planechase 2012 Planes (OPC2), collector number 10. Current market price: $3.75, TCGplayer market prices via Scryfall.
When you planeswalk to Aretopolis and at the beginning of your upkeep, put a scroll counter on Aretopolis, then you gain life equal to the number of scroll counters on it. When Aretopolis has ten or more scroll counters on it, planeswalk. Whenever chaos ensues, put a scroll counter on Aretopolis, then draw cards equal to the number of scroll counters on it.