Chariot: If the preamble is to be believed, The Mystic Art of Rebreathing is a technique developed by alchemists to safely work with more poisonous and vaporous materials without fear. By magically reinforcing the lungs, and with a bit of a unique breathing excerise, one can learn to hold their breath for a maximum of 30 minutes with minimal movement, 20 with light activity such as walking, crafting or otherwise, and 10 minutes of rigorous activity such as running or even fighting. Given the thickness and the reference to benchmarks, this book will probably take 8 hours of reading and practice to utilize.
Banshee: Tremor Sense: Beginner seems to be the ground work for a greater technique. At this level it seems to send magically enhanced sound waves through the earth to give a picture of 30 feet around the user. It only works with things touching the ground but otherwise can be used to detect hidden things, such as hidden passages. It is very loud though.
It’s complex and due to its thickness looks like it’d take about 8 hours to read and utilize.