Awesome card for a miniature that haven't been released yet... >.<

Are these mechanically any different than what comes in expansion? Or just alt art?

All tournament cards are just alt art. Ffg will never give you a new card through a tournament.

All tournament cards are just alt art. Ffg will never give you a new card through a tournament.

They did say they would be giving put errata'd royal guards and sabs.

Which are still only alt arts compared to the legal variants and the variants future players with new reprints of the core box you will have.