Cliffside Market is a common Plane — Mercadia card from Planechase Anthology Planes (OPCA), collector number 18. Current market price: $5.65, TCGplayer market prices via Scryfall.
When you planeswalk to Cliffside Market and at the beginning of your upkeep, you may exchange life totals with target player. Whenever chaos ensues, exchange control of two target permanents that share a card type.