Can you make effective poisons/acids/flammables from basic ingredients that would be useful in fighting monsters?
I am writing a story about a MC who goes into Portals to kill monsters (Typical DnD setting: Orcs, elves, etc.) before exiting the Portal again to get back to earth. He is a basic dude with an average IQ (basic medical training, nothing more).
He wants to make Poisons, acids or flammables to fight the monsters, but can only make them from the ingredients/resources he found inside a Portal and brought back with him. (Earth materials cannot enter the Portal).
He’d have access to local flora and fauna, the corpses of monsters, basic metals such as iron or copper, bits of rocks, etc that he can bring back with him.
He can process the material back on earth where he’d have proper equipment and can do research on it, but I’d prefer it if he could do it on his own, not hire the world’s greatest chemist.