Unstable Frontier
Land
: Add 
.
: Target land you control becomes the basic land type of your choice until end of turn.
The goblins went to sleep in Jund and awoke in Grixis. They'd never seen a zombie before. They would never see one again.
John Avon
The List (PLST)
• #CON-145Rulings
The affected land loses its existing land types and any abilities printed on it. It becomes the chosen basic land type and now has the ability to tap to add one mana of the appropriate color. Unstable Frontier's ability doesn't change the affected land's name or whether it's legendary or basic.
(wotc • 2009-02-01)
You choose a basic land type as the ability resolves.
(wotc • 2009-02-01)
Rulings
The affected land loses its existing land types and any abilities printed on it. It becomes the chosen basic land type and now has the ability to tap to add one mana of the appropriate color. Unstable Frontier's ability doesn't change the affected land's name or whether it's legendary or basic.
(wotc • 2009-02-01)
You choose a basic land type as the ability resolves.
(wotc • 2009-02-01)