Green already has a lot of creatures that produce mana (Innistrad Remastered's Somberwald Sage is one that just didn't quite make the cut for this list), but what if all your creatures could produce mana
The Fertile Lands of Saulvinia, Antausia Antausia is a plane that went unrecorded up until early 2019
On top of that, playing Familiars means you often get hit by hate aimed at High Tide
After solving the Millennium Puzzle, his body ends up hosting a mysterious spirit who also enjoyed games and gambling
Shards of Alara can be summarized as gold dialed up to eleven, or in this case three, and Alara Reborn turned the dial all the way to one hundred
Devotion decks are notorious for generating a frankly ridiculous amount of mana, so anything you can sink your mana into is an extremely attractive inclusion