You also wouldnt play Llanowar Dead over Three Visits as Three Visits only requires green mana, it can fetch lands that tap for multiple colors, and its ramp effect isnt tied to a creature that will likely disappear after your games first board wipe
While the second mode is rarely worth using, for three life is hardly worth one additional mana, it's still nice to have the possibility for it to become a board-wide protection spell if you needed it
Eater of Days only belongs in decks that want you to give away your own cards, but you have to do it in a way to trigger the enters ability to make your opponent skip two turns
You can run the latter as your Commander, which essentially makes this a one-card combo if you do so
The second part here is the real deal
For example, we've already seen some of the Outlaws of Thunder Junction Special Guest cards in the form of a cowboy-hat-sporting Notion Thief and Port Razer