That's the UK DVD edition. I ordered it because the listing shows this artwork, and when I asked Amazon customer service, the agent confirmed it was a slipcover
When I received it, turned out that the art shown was on the amaray rather than the slipcover
@goufcustom If you want that Monster Mayhem slipcover, it's available on the US blu-ray edition (I know it's a slip cos I got it then gave it away last year during ninja week)