velotha's flock has been in development for a while, and it still has two planned products in its product line: an advanced play guide and an adventure/setting manual.
Right now, I've been putting a lot of time into the advanced play guide, and I expect it to be done before the end of the week (and by "end of the week" I mean "before I fall asleep on Sunday").
I made this handy little reference because I was having problems working on the pre-made characters because it involved way too much back-and-forth.
It's a PDF with comments that contain the appropriate rules content for pretty much every special ability in the game. Because it contains a lot of the context, it's also a first glimpse at the advanced play guide, because it contains all the abilities and basic rules for making characters using the new system, though I wouldn't suggest trying to use it as such right now.
The biggest problem with it is that the majority of mobile and web-browser based PDF readers will not load the annotations (Chrome and Firefox do, though this might be working for me and not others, as should any major desktop PDF reader; it looks like Microsoft Edge, Safari, and Kindle do not load comments from the PDF), and actually including the rules text that those annotations contain would get so bulky as to defy practicality. Rewriting all the abilities in shorter format would be nice, but it's also a pretty hefty task and not on the road-map.
As a result, this is the best we're going to get for now. You can download the PDF here.
Image based on a public-domain drawing of a raven (which I acquired from the NYPL archives) that has been adapted to black/white.