I was a bit surprised to see this very rare giallo turning up on a gorgeous looking Italian dvd a while back. There is no English option, but luckily enough master fan-subber Merlin did subs for it and I was finally able to see it. Certainly no classic, but it's enjoyable and stylish yarn about a gang of criminals who are holed up inside a castle to divide the loot but are being picked off one by one. Slightly odd size to the poster. It's bit smaller than your usual locandina.
No info on the poster artist.