This pdf is 31 pages long, 1 page front cover, 1 page editorial, 4 pages SRD, leaving 25 pages of content, so let's check this out!
After elaborating for quite a bit on my personal relation to random encounters in my reviews of the first two random encounters remastered files, I'm going to limit myself to a more basic reviewing approach here: Essentially, this pdf provides HUGE tables for different terrains, including hazards and beasts. For your convenience, the creatures come with their source-book mentioned as well as an average CR-rating.and we're speaking about tables that go up to e.g. 480+!
That's not all, though, for the series also features terrain features and so-called dispositions. Dispositions are a kind of modular template you add to an encounter like "disguised" etc. Tables including e.g. clues for encounters etc. are included as well and random tunnel directions should be noted among the cooler features of the general section of this pdf along-side rules for flash-floods, mirages and sinkholes.
Terrain-wise, this time around we visit the bowels of the earth, endless caverns, highlands, scorched wastes, teeming veldts and windswept plains.
Editing and formatting are top-notch, I didn't notice any glitches. The pdf comes in Purple Duck Games' 2-column standard and the b/w-artwork is ok. The pdf comes with extensive bookmarks and is small enough to be used on an e-reader. I really like this series, as it is a great way to enable a DM to spontaneously create random encounters that are detailed, challenging and don't feel as amorphous as regular random encounters. However, not all is gold in this pdf: While I enjoyed the focus on subterranean terrains and plains in this pdf, the overall hazards and terrain felt a bit less inspired than in the 2 predecessors - unique terrain-features like side-arms of Styx and similar terrain-specific hazards are mostly absent from this file and I would have loved to see more dispositions in this file. Overall, this book is good, but slightly less good at what it sets out to do than the 2 predecessors. Thus, my final verdict will be 4 stars.