Tidewalker is a uncommon Creature — Elemental card from Planar Chaos (PLC), collector number 49. Current market price: $0.29 (foil $0.69), TCGplayer market prices via Scryfall.
This creature enters with a time counter on it for each Island you control. Vanishing (At the beginning of your upkeep, remove a time counter from this creature. When the last is removed, sacrifice it.) Tidewalker's power and toughness are each equal to the number of time counters on it.