To clarify (since this problem is clearly not evident to hundreds of others):
By every time it takes damage, you mean every session in which it takes damage, not every point of damage it takes, right?
I like this card altogether. It offsets the whole Fire creatures having low health thing, so that's both a plus and a minus in how good it is. It helps an element in an area where it needs it, but thematically, it might not fit. I'm not sure how to work on this.