The three Legendary rares in Planeshift were unique in that the premium (foil) versions have different art than the regular versions. Here are both versions of each card, side-by-side.
Ertai the Corrupted
Regular version by Mark Tedin, premium version by Kev Walker.
Tahngarth, Talruum Hero
Regular version by Dave Dorman, premium version by Kev Walker.
Skyship Weatherlight
Regular version by Mark Tedin, premium version by Kev Walker.