Gather 10 bushels of Incendia Agave, and then consult Magatha Grimtotem on Elder Rise in Thunderbluff.
Arikara is a deadly creature that must be dealt with swiftly. In order to hunt her down you will need to light the sacred fire of life - this will summon Arikara.
Go now and harvest the rare Incendia agave plant. Once you have harvested enough agave, seek council with Magatha Grimtotem on Elder Rise in Thunder Bluff. She is a powerful shaman that can enchant the agave plant to create a powder that will light the fire.
Travel northeast to the Boiling Pool and gather Incendia Agave.