Finding all 8 Bomb Formula locations and buying them up will help unlock the following Achievement / Trophy: “Bombardier” (15 Gamerscore / Bronze Trophy) — Collect the formulae for 6 different bomb types.
How to find missing Bomb Formula?: You can simply buy 8 Bomb Formulae from a herbalist. The best location is at the “Herbalist’s Hut” fast travel point in the south-east of Novigrad. Talk to him and ask “Show me what you got.” Then look for the manuscript pages in his inventory, they are described as: “[Magic Item; Alchemy Formula] Formula for crafting a bomb that explodes on impact.”
Note: He offers 8 different Bomb Formulae. This will cost you around 2,000 Crowns for each Bomb Formula.
The Manuscript Pages for the 8 Bomb Formulae are named:
• Dancing Star
• Devil’s Puffball
• Dimeritium Bomb
• Dragon’s Dream
• Enhanced Grapeshot
• Enhanced Samum
• Moon Dust
• Northern Wind
Tip: You can simply create a backup save before doing this and sell all your crafting materials / alchemy ingredients to the merchant, then buy the formulae with the money. Reload your save game to get the money back.
Where to find all Bomb Formula in The Witcher 3? The in-game locations for the Bomb Formula are shown in this detailed video guide.
Credits: Special thanks to Powerpyx for the tips and video guide.