Kenner rebranded the existing 21 figures one last time before the release of The Empire Strikes Back. These cardbacks would include the new Empire Strikes Back logo treatment and an offer for a free “secret” action figure from the upcoming movie.

A burst printed on the front of the cardback disclosed the offer while the back detailed redemption instructions.
 

 
Refresh stickers for front and back were issued, creating a 21c, making the Empire 21 Back 21d.
 

 
The offer was extended, requiring a refresh sticker to be attached to any instances of the offer whether printed or refreshed. The sticker appears to be identical to the second refresh sticker on the Boba Fett offer cardback.
 

 
This extension would push the offer past the release of the first Empire assortment, which included Bossk (the secret figure). Kenner provided another refresh sticker identifying the “secret” figure as Bossk so as not to disappoint fans with a potentially duplicate figure.