(the magic book)
... And I would gladly recommend it to my worst enemy. I might throw some of the juicy bits at @bad-mtg-novels if @rhys-the-redeemable asks me to, but one of the frustrating part is that the author clearly had some cool ideas, so they wrote them (with his own, very particular, style). Regardless of their relevance to the plot or of the card game in general. As such, among other things, the book introduces a lot of sentient species that never were acknowledged in the card game or in other books, because he wanted to. It does provide some original species for characters though...
Elen: Broader classification Aven subspecies. 9-10 feet tall, heavily muscled, have only vestigial wings, incapable of flight
Raypen: Broader classification Aven subspecies. Dwarf sized. Capable of flight with magic help. Fast and agile
[Unnamed] : giant (non humanoid) geckos capable of clinging to any surface, incapable of human speech. Main body as large as a horse's, but much longer.
Anurid: massive humanoid-ish frog, very limited intelligence. Those actually show up on cards.
Whales: Regular whales. Sentient. Capable of performing sound magic through their song.
Various types of more-or-less humanoid crabs, corals and other kind of seafaring beasts
Tresias: small humanoids with sharp claws on their hands and feet, lots of teeth, pupilless blank eyes more adapted to deep water than anything. Fast and nimble
I might have forgotten some along the line.