Green decks have so many ways to make land drops and maximize these creatures, especially since their respective counter doubling abilities effectively remove any ceiling one might place on them
It can't reduce requirements of specific colors of mana
I undoubtedly left off some of your favorites
You name a non-land, non-artifact card, and search your opponent's library, hand, and graveyard for any card with the same name and exile them
We recently saw Psychic Possession soaring in price, and before that a very narrow counterspell spiked surprisingly hard
If an effect allows a player to cast a spell without paying its mana cost, that player can't choose to cast it and pay its mana cost unless another rule or effect allows that player to cast it that way