I've rereleased the bestiary for the first 250 episodes of my podcast with the legalese for the Open License attached. This means if you're a creator you can dig into it without worrying about rights issues. It was originally called "Little Demons" then when I enlarged it I called it "Half Remembered Monsters". The new title is "Ars Magica Monsters Volume One". It's free on Patrteon at https://www.patreon.com/posts/ars-magica-one-114759510 and will eventually be on Drivethru as a "pay what you want but I'd like a dollar" thing.
It's called Volume One because I have 504 podcast episodes, and a list of monsters to stat up as long as my arm.
As I see it, my Patreons have already ransomed this. So: 96 monsters. Have a look and a play.
A discussion of what the final version should include is over at Ars Magica Monsters Volume One