Grafdigger’s Cage prevents players from casting spells from the graveyard or library, as well as creatures from entering the battlefield from a graveyard or library. This is a static ability that changes the rules of the game for as long as the Cage is in play. This means that it stops a lot of things in standard, such as (this sample list is not comprehensive):

• Cards with flashback can’t be cast from the graveyard
• Gravecrawler can’t be cast from the graveyard
• Havengul Lich won’t let you cast a creature from a graveyard
• Green Sun’s Zenith can’t grab a green creature from your library and slap it onto the battlefield
• Undying can’t return creatures to the battlefield when they die
• Unburial Rites can’t return anything to the battlefield
• You can’t cast creatures from the top of your library with Garruk’s Horde

Note that this only specifically restricts creature cards from entering the battlefield from the library. The Cage has no interaction with anything that searches for lands (e.g., Solemn Simulacrum), and it doesn’t care if you return a creature card from your graveyard to your hand (e.g., Ghoulcaller’s Chant). Similarly, searching your library for a creature to put into your hand with Garruk, the Veil-Cursed is not a problem.

Today’s Rules Tip written by
Ronny Alvarado, Level 2 judge from Houston, TX