You can drop another land each turn and then tap it with six mana to dig six and drop, for free, a dork with a mana value equal to or less than your land count
Typically however you want your top end at 7 and 8 if you want casting them as a backup (which the green based cheat in decks generally do)
By paying a cost of one life and sacrificing the fetch land, a player is granted the ability to delve into their library to retrieve a land card of a specific basic type, such as a forest, mountain, island, swamp, or plains, and put it directly onto the battlefield
Both produce unspeakable amounts of mana with a little help from some of the most common card types in the game
XY (2014) The debut XY set brought Kalos starters, Fairy-types , and a fresh energy to the game