Ooh this is a fun one! Presentation is simple, nice and legible. Some more usage of bold or italics would help items and monster entries stand out more. I love the artwork, especially the marginalia style! The concept itself is really cool and I love the DCC style weird fiction sci-fi flair.
I like the addition of powerful magic that could also be used by others, provides some good setup for rival encounters and could lead to some interesting dynamics on a domain level. really fun stuff!