Fertile Ground is the worst one by far but is in here for budget concerns, a concession that must be made for 150-dollar decks
In Commander with a creature as your leader that's a guaranteed +1/+1 which could be a faster Commander Kill by a turn so it's a Time Walk in mana dork form
Commanders like Titania, Protector of Argoth, Yuma, Proud Protector, and The Gitrog Monster want to throw lands into the graveyard for additional value
That means that you can usually ultimate your 'walkers as soon as they arrive, and many of them are game-ending
Its a bit better than that, and it subtly gives some hate to the decks that revolve around interactions with tokens like Treasure tokens, or even Clue tokens
Turn it face up any time for its disguise cost.) When this creature is turned face up, you may tap or untap target creature