This limited edition promo card features Bastas from Patrick Rothfuss's The Kingkiller Chronicles.
Bastas is an Epic Hero, class Thief.
This card was released for a limited time only, along with its Ordinary Hero counterpart Bast.
From the website description:
Introducing the brand new, limited edition "Bast" and "Bastas" hero cards for Boss Monster, a dungeon-building game inspired by classic video games.
Designed and donated by Brotherwise Games, these cards are available exclusively through our store, and they are in limited supply! Claim yours while you can!
The game itself is not included in this item. If you don't have the game yet, you can get the game and the cards together over here: Boss Monster Game.
All proceeds go to Worldbuilders.