u/Oh_Hi_Mark_

For nigh on two years now, I've been noodling away at this infernal tome and it is finally fit for mortal eyes; BEHOLD!

Within its pages, you will find devils and spells and arcane items beyond number, stat blocks for every archdevil, travel guides and maps for each of the nine layers of Baator that matter (don't ask me about Phlegethos), and all manner of supplemental tools and goodies for infernal sojourns.

It also comes with free VTT modules for Foundry and for another website I'm not sure I'm allowed to mention here.

• Hell Awaits - The Book of Devils (Works decently on mobile, but the table of contents doesn't work unless you download the PDF)
• Homebrewery Link (All the links work, but the formatting gets funky unless you're on desktop chrome)
• Downloads (PDFs, VTT Modules)

Should this fail to sate your appetite for monsters, I have more such free books:

• Howl to Ruin - The Book of Demons
• Death Denied - The Book of Undead
• Terror Unto Madness - The Book of Aberrations
• Dictates of the Ordning - The Book of Giants