Wormhole Warp

Playtest cards use a modified version of game symbols, such as {T} and {W}. These modified symbols should be treated as the standard symbols during play.

In Limited play, each card in a player’s card pool that isn’t included in their deck is in that player’s sideboard.

If the target creature’s controller doesn’t have a sideboard, perhaps because you’re playing a format that doesn’t use a sideboard, they won’t reveal or cast anything. (That sounds pretty good!.)