Willow is a fun character, having a massive teddy bear bodyguarding you for some time is fun stuff, but she is still missing something that coulld define her as the "firestarter" character.
she has the fire immunity, which is rather rare to come across, However, if you want willow to burn forests (which has a potential to be a good fighting technique, and if you dont, well, there's not really much of a point to have it in my opinion), you should make sure it is at least effective. What i would suggest is her flames (of flames in general) to do either higher damage, more time to be burning and a higher chance or a wider range, where the flames can set you on fire.
willow to me is a glass cannon character, you mess something up, and instead of a safe fiery haven, you have your whole house burned down, and i like that kind of idea, it makes people look at the game differently, with a unique playstyle, and a unique strategy to fight things, all she needs is to have her flames mean something, and not just destroy property (hence i think the griefer character).
all i have here is a suggestion, you dont have to take all in, or anything in particular. i am just pointin out some flaws i see in that good-potential character.
i expect some feedback about this message from other members aswell, just so it can become real with even less flaws, than if it had when i posted this topic