In practical play, though no powergaming, I am finding that Fire attacks achieve much more rapid kills than frost/lightning due to this effect, as after the first volley, the follow ups, if done fast enough, are doing something like 1.5-2 times damage.

I find the only time frost is better is versus a 2-hander melee npc for the slow effect, or versus a fire dragon/flame atronach. Lightning's secondary mana draining effect is worthless versus mega npc mana regen, so that just gets used for its insta-hit speed against fast moving or long range targets that are hard to hit with fire.

But when the time comes to lay on the hurt asap, fire trounces these other damage types by quite a margin it seems,

my question is: WHAT IS THE ACTUAL MECHANIC? it seems quite chance based, almost like critical strikes for weapons.....

one and only bump- cause this went to page 3 in under 10mins i think...lol