This limited edition promo card features Bast from Patrick Rothfuss's The Kingkiller Chronicles.
Bast is an Ordinary Hero, class Thief.
This card was released for a limited time only, along with its Epic Hero counterpart Bastas.
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!
All proceeds go to Worldbuilders.