Well, the top colorless Commander staples that are also mythic rares are Mana Crypt, Mana Vault, Sword of Feast and Famine, Wurmcoil Engine, and Crucible of Worlds
Most land destruction in green these days (and "these days" hasn't been in a while) is "destroy target noncreature permanent." "Lhurgoyf" (This creature's power and toughness are equal to the number of cards in your/all graveyards.) Primary: Green Secondary: Black Tertiary: White, blue, and red Lhurgoyfs started as a green thing and have since gone on to also be a black thing
With the advent of fast decks such as Beedrill, Machamp, and Luxray/Infernape, your Pokmon are going to be KOd quickly and often
Since the trigger isnt restricted to once per turn or anything dull like that, you can squeeze multiple cards from a single combat relatively easily