Yeh, the Searing Flames boss totally eradicated me the first time...
Try to get an interrupter, give Margrid Broad Head Arrow would be a decent solution, but I've found an even better one.
I hope that you have prophecies, so then you can get Olias...
Set him to N/Me, and give him loads of interrupts, I gave him Power Block, Power Return, Power Spike, Cry of Frustration, Mistrust, res sig , power drain and backfire... he hardly used backfire, and it wasn't needed anyways... he singlehandedly kept that ele boss down by interrupting the guy 5 times in a row, the fifth interrupt being Power Block. He didn't do squat, and was a pushover when he's getting interrupted
Also, a trapper wouldn't be a bad idea, before you lure...