Cold Storage

{3}: Exile target creature you control.
Sacrifice this artifact: Return each creature card exiled with this artifact to the battlefield under your control.

The List

Tempest

o3: Put target creature you control on Cold Storage.
Sacrifice Cold Storage: Put all creature cards on Cold Storage into play.

If it exiles a token creature, the token ceases to exist and will not return.

If this card leaves the battlefield, the cards it exiled remain exiled.

For a time, the second ability returned all cards exiled by it to the battlefield, regardless of what types they had while exiled. It has been restored to its original functionality, so only cards that actually have the type Creature will get returned.