anonymous asks: Has Keyleth ever received any benefit from her crafting book she bought?
Short answer: Yes!
How much use she’s gotten out of her books depends on which ‘crafting’ book you’re speaking of. In Episode 15, she purchased a book on herbalism and a book on animal extraction. In Episode 24, she purchased a book about the properties of chemicals and liquids, and an introduction to sorceries book that had a chapter on alchemy.
Her goal of learning how to craft her own potions has been largely set aside for the time being. This is namely because Vox Machina had to hideout in Whitestone with no access to materials for so long, then had to search for Daxio, then check into the house, and then deal with the dragons. However, she did craft her first Greater Healing Potion in Episode 27 (2:31:52) thanks to the the knowledge she gained through reading all of the books she bought dealing with alchemy.
Arguably, she’s thus far reaped more benefits from her book on animal extraction. When she uses it, she gets advantage on rolls for extracting any parts from animals, and it gives her insight on what parts are valuable from those creatures. She successfully utilized it when carving up the phase spiders in Episode 16 (2:20:41), Hotis the Rakshasa in Episode 21 (3:49:53), the behir in Episode 28 (0:59:13), the frost worm in Episode 39 (1:38:49), and the wyverns in Episode 42 (2:17:30).
Update: Confirmation from the half-elven druid herself: “It gives me advantage on nature check when attempting to harvest anything.” Thanks, Marisha!
Update 2: Keyleth created her first Potion of Fire Resistance in Episode 45 (2:26:36).
Thanks to @nevyndoc for the reminder about Episode 42!