I like the idea, but this is such a white mechanic that I have a hard time seeing blue do this. It's especially vexing, since this is one of those things blue really wants to do (get more lands) and is denied, since that encourages players to play two color decks.

I do admit, though, that if this card was white, it would probably search for Plains only. I'm not really certain what color I'd use for this the way it's written... though I suspect Wizards would wait for a multicolor set and cost it . I also get the impression that this card became blue due to 'Treasure Maps' -> 'Pirate' -> Blue. I don't see any reason one has to follow that formula religiuosly, though. I like it when flavor has to go out of color for legitimate reasons.

This is crazy with Valakut, the molten pinnacle if you're somehow behind. I bet a deck could abuse that combo somehow.

Yeah, it definitely needs work. It was an attempt to help out colors other than green take more advantage of the Explorer mechanic. Maybe it needs to have more stealing in it.

The idea was waiting for your opponent to map out the land, then sneak in and steal those maps, getting the lay of the land while the opponent does most of the work.

If this searched an opponent's library for the land, I would have less of a problem with it being blue.