https://www.youtube.com/watch?v=qCEOk3kYXb8&t=2m13s
That shows in the 10s that flamethrower is going off it deals 11 ticks. I'm not sure if the ticks are calculated as 120 potency or 60 potency but they seem kinda high (High 800s low 900s) compared to the auto attacks (1k~1.3k).
Also another thing to note in terms of openers, It has not been stated whether or not we can preload heat with flamethrower. If that is the case we could potentially start the fight with 70 heat, leaving flamethrower to be used after wildfire to get you back into the 50% zone.