i was just iplementing it into Black Core (over 200 skills to configure, took a while) and i was just thinking about a suggestion,
what i thought of is maybe multipling the threat depending on the element so say a monster's Fire element defence level is A, Ice element is F and the rest C, if the monster is atatcked with a fire element skill, the threat goes up by x3 more (because it is it's wekaness) while when attacked by an ice skill, it goes down my x-3 (because it absorbs the attack, no threat and most liekly to ignore that chater so it can keep getting attack and healed up like that)
so it works like this
A = x3
B = x2
C = normal
D = -normal (or x-1, which ever you want to call it)
E = x-2
F = x-3