If Fecund Greenshell's second ability stops applying (because Fecund Greenshell leaves the battlefield or loses its abilities or because you no longer control ten or more lands), then any creatures that needed the toughness bonus to stay alive will die
It might be borderline impossible to collect a single copy of every Magic: The Gathering card ever printed, much less a playset of every card, but if you've ever wanted to build out a set, like a collection of a specific set, it could be something like a challenge to collectors
In fact, many of the best stuff running around is oriented toward the big side (Stoneforge Mystic, Restoration Angel, Teferi, Mage of Zhalfir, Consecrated Sphinx, Vampire Nighthawk, Gray Merchant of Asphodel, Feldon of the Third Path, Azusa, Lost of Seeking, Silklash Spider, Courser of Kruphix, Prophet of Kruphix, Brago, King Eternal, Kuldotha Forgemaster), and thats in addition to creatures specifically designed and included for defense like Walls and other cards with defender
TCGPlayer places the valuation for the Enchanted Shere Khan: Menacing Predator at $183
This price movement is much more erratic than the S&P 500
