KOTS- Dervin's Boot of Salvation

This was one WEIRD situation from a D&D session. so we're going down a dungon hallway and we come to a large hole in the stone floor. So me, the ranger guy in the front ther, Owen and a few other go down there to see what's up (no pun intended.) We find a water elemnetal and it begins to kick the shoot out of us. Joy. But that's not the point. Meredith, decided to try to use a "Potion of Fire Breathing" that we found that was like 300 years old so aparently it was more potent now. So she rolls her save and fails critically and poof her entire body is on fire. Fortunatly there was water in the chanber below AND Dervin, our neutral-good Druid was standing next to her and BOOT! She's out. Almost dead, but not on fire.