Spatial Merging is a common Phenomenon card from Planechase 2012 Planes (OPC2), collector number 7. Current market price: $0.78, TCGplayer market prices via Scryfall.
When you encounter Spatial Merging, reveal cards from the top of your planar deck until you reveal two plane cards. Simultaneously planeswalk to both of them. Put all other cards revealed this way on the bottom of your planar deck in any order.