10 Rocket's Mewtwo - Gym Challenge Set One card that players may have forgotten about from the 2000 Gym Challenge set is Rocket's Mewtwo
Current market prices put Fez at $15, as almost every single deck plays this bird, so this one card already pays for half of the boxs cost
Heavy-played commanders like Voja, Jaws of the Conclave or The Wise Mothman can put +1/+1 counters on each creature you control, so Inspiring Call is perfect in those decks
In fact, BGS 9 copies have sold for over $1000 recently on eBay
Jan Jansen, Chaos Crafter Jan Jansen, Chaos Crafter gives all the aristocrats players an entry point to artifact decks
For me, its more about enduring impact, and unless Modern Horizons ushers in a ton of support for cheap, recursive creatures, I would guess it falls a bit short