So, this is my first time posting, this isn't necessarily an exploit but there are things called Pools of Fire in the Twilight Highlands that guarantee a volatile fire EVERY cast. You do NOT have to be high level fishing to fish in these pools and be able to fish a volatile fire.
I will post a screenshot of the location and what they look like whenever i get out of this queue. Sorry if this is a repost but I searcher volatile fire and got nothing of the sort. The basic location of the pools is in Cannons inferno in the southwest area of Twilight Highlands (the purple area with Bastion of Twilight in it)