Slipstream Serpent is a common Creature — Serpent card from Time Spiral (TSP), collector number 77. Current market price: $0.05 (foil $0.35), TCGplayer market prices via Scryfall.
This creature can't attack unless defending player controls an Island. When you control no Islands, sacrifice this creature. Morph {5}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)