Some of the quills from a Quilltoad's back are likely to be left behind when it combusts. Try to collect 30 of these, and hopefully some specimens will still contain the poison to study.
Luckily we have medicines like Acid Phosphate and Elixir of Vitriol that cure a variety of poisons, but I'd still like to learn more about the poison that que Quilltoads have in their quills. If you have the time, could you help me gather some quills from these creatures?