Storm Cauldron

Artifact

Each player may play an additional land during each of their turns.
Whenever a land is tapped for mana, return it to its owner's hand.

2004-10-04:
If a land is tapped for mana and sacrificed all in one action, it goes to the graveyard before the Cauldron can return it to the player’s hand.
2004-10-04:
If a land is tapped for mana, it is returned to its owner’s hand as a triggered ability.
2004-10-04:
Having multiples of these on the battlefield means you can play an additional land for each one.