Mystic Compass, a highly underrated card from Alliances.
Your typical player will not counter the compass or shatter the compass because he assumes it is chaff. (he may be right :) )
When a land like Lake of the Dead re-enters play after being changed into a basic land from the compass it will not trigger the 'sacrifice a swamp or bury' effect. The lands are not considered to be re-entering play, it is the same thing as the land phasing in.
Remember Mystic Compass only works on mana producing lands, it will not work on cards like Glacial Chasm and Halls of Mist.
Mystic Compass can not save a Mishra's Factory from dying by turning it into a basic land.
Here is a ruling:
* If an Assembly Worker is changed into another kind of land by
something like Phantasmal Terrain, it will stay a 2/2 creature but
will not still be called an Assembly Worker. [WotC Rules Team
11/10/95]
Here is a summary of Mystic Compass' uses:
- Landwalkers of every color can use it cheaply and unlike phantasmal
terrain he can't sac the land to his Zuran orb to shut down your landwalkers
permanently (though he can do it each turn and lose lots of lands).
- This includes cratures with landhome and creatures like seasingers.
- If you have dark heart of the woods and not all forests you can sac
a land to gain 3 life after changing it to a forest.
- If you don't have the right color of land out you can adjust so that
you get the color of mana you need. (Same cost as celestial prism basically)
(remember this is at instant speed though, not mana-source speed).
- If you have lots of alliances lands in your deck and don't have the
right kind of basic land to sac then you can make a basic land with the
compass.
- If opponent has 2 blue untapped then change one to a green.
- If blood moon is out and you need a white to disenchant it, you got it.
- One less damage against primal order.
- If casting stench of evil of tsunami or flashfires you can kill an extra
land for each Compass you have out.
- Can be used during opponents upkeep to deny him a color if he only has
1 land of that color.
- Can be used to get several Sheltered Valleys into play.
- Here is a theme deck based on it: Kormus bell, rod of ruin or tims, possibly add illusionary terrain or jinx to help change lands to swamps. Simply ping all his lands after making them swamps. (ok its not a tournament deck :)
Special thanks to all those who gave me ideas and criticism (Joe Fulgham, Ian Sulham, and others)