I agree that the way it is currently can be pretty weird -- damage should be based on time spent, not movement.
Example 1: I cast Firefly in a straight line in an open field; an enemy crosses it perpendicular to the line, crossing the minimum amount of fire to reach me.
Example 2: I cast Firefly across where an enemy is standing, and they move away from it immediately on their turn.
Example 3: I cast Firefly across where an enemy is standing, and they stay in it during their turn (to attack, use items, save AP, or they were knocked down or stunned).
Example 4: I cast Firefly to fill in a choke point between lava patches. An enemy has to cross several meters of fire to reach me.
The way the game works: example 1 does damage once. 2 does damage twice. 3 does damage once, plus once more for every turn that the enemy remains in fire. 4 does damage once per "step" taken.
The way it should work: example 1 and 2 should do damage once. 3 and 4 should do serious damage, based on time spent in fire.
I think it's important, tactically, that example 4 do far more damage than example 1. But you shouldn't be able to stand around in fire casually because it's only going to tick once per round.
