This is wild. Casually dropping a 1980s fantasy hack in two columns -- what do I even say? I'm stunned.
I'm afraid I don't have much feedback for you. I don't see this taking 2-3 sessions, but I guess Warden-styles and session lengths will vary. In the miscasts, is it intended that miscasts can reduce stress? Gaining stress seems like it might be more on theme. There are a few places I'd add capitals in the Loadout lists, and I think Ammit and Horus could both have been fleshed out just a bit more. But then again, it's a pamphlet, and it's already jam packed with great stuff.
Very neat! I'm excited to see what you do next.