Riptide Island is a common Plane — Dominaria card from March of the Machine Commander (MOC), collector number 64. Current market price: $5.68, TCGplayer market prices via Scryfall.
When you planeswalk to Riptide Island and at the beginning of your upkeep, create two 1/1 colorless Sliver creature tokens. Whenever chaos ensues, Slivers you control gain haste and get +X/+X until end of turn, where X is the number of Slivers you control.