Prairie Stream

In Commander, Prairie Stream is a respectable budget dual in any white-blue shell — it enters untapped often enough to pull weight and carries both the Island and Plains subtypes, which matters for fetch compatibility with Flooded Strand and friends. In Legacy and Vintage, the fetchable subtype is the point: Prairie Stream can be found by any blue or white fetch land, which makes it see occasional play in multicolor control sideboards when shock lands are cost-prohibitive. In Modern and Pioneer, the competition from shock lands and pain lands is stiff, and Prairie Stream's conditional untapped clause makes it a clear third choice — playable, not preferred. Pauper and Standard don't apply, so the card's practical homes are Commander and fetch-heavy eternal formats where the Island subtype does real work.