Looks great - I prefer simple adventures as it gets non-gamers into it. Two ideas, though:
1. Pre-generated characters for players to choose? A "knight" (fighter) and a "wizard" (magi) are simple concepts everyone is familiar with.
A very good idea, but I didn't add it for a few reasons - there are already 'starter' characters in the ML20 Player's Guide, I wanted this to be usable for any characters, and rolling NEW characters is SUPER fun.

2. The Magic Ring at the end is +1 MIND (stat score, presumably). That's pretty powerful! It may not matter for a one-shot adventure, but if you want to turn it into a campaign, maybe try +1 to magic/supernatural attacks, or cast one spell without spending hit points "X" times per day, or something like that...
Thanks for the heads-up. I came up with that on the spur of the moment, and I am still getting to grips with balance in the game. One of my favourite things about this system is how easy it is to adapt these ideas on the fly, and adjust as you go.
I think I may weave that change into my son's artefacts post-hoc. We are scheduled for our 6th adventure in this campaign soon!