Longtusk Cub Longtusk Cub can go the distance, and this green cat was very problematic in Standard
Even discounting all three of her Loyalty abilities, shes still an absolute slam-dunk for the format
Blast from the Past (Green-White-Blue) Timey-Wimey (Blue-Red-White) Paradox Power (Green-Blue-Red) Masters of Evil (Blue-Black-Red) You can browse the cards in these decks with the Magic: The Gathering Doctor Who Card Image Gallery, including their showcase treatments available in Collector Boosters
And while not every card can pull in a four or five figure asking price, the rarest ones certainly can, making the whole catching-them-all thing definitely worth the effort
(Synergy with the landfetchers above.) Highland Lake, Swiftwater Cliffs, Temple of Epiphany, Timber Gorge and Woodland Stream could be these utility lands instead: Mosswort Bridge, Myriad Landscape, Blighted Woodland, Kessig Wolf Run, Littjara Mirrorlake