Random prismatic pack found in Asda

Was shopping in Asda Robroyston this afternoon and after picking up a shrouded fable box, I found a random prismatic pack lying on a shelf. I asked the staff if they had more but apparently it wasn’t on their system so they think it came from a magazine. As far as I’m aware you can’t get these in a magazine so they gave me the pack anyway.

Just wondered has anyone bought prismatic from Asda?