Burning/Poison/Cold damage

[Xargon]

Does someone have the exact formulas for burning/freezing/poison damage? What does it depend on, when is it a flat percentage of the troop's health, and when is there some maximum?

Something awesome just happened in my game: I fought an invincible stack in the boot dungeon in Freedom Islands, it had one stack of 7k thorn hunters. First round, I cast greasy mist and Gudrida's rage, inflicting about 3k damage and (this is the important part) setting them on fire. When it was their turn, they received... a critical hit of 32k burning damage, killing about half of the stack. Compare that to the 3k (or maybe 4k against thorn hunters) my Royal Griffins would deal with a crit. (the burning medal is at lvl2)

Is the burning form rage skills always a percentage, no matter the amount? I got the impression that effects inflicted by unit skills or spells are capped at some amount.