Im just going to put my 2cents out there.

What i would like to see, is creep damage types become a toggle skill.
For example my class the reaver.
Fire is awesome against heavies etc, but when it comes time to fight a lets say, a minstrel, fire is not getting me anywhere.

A toggle skill that would not have to be instant and could have a decend cd on it, not like Blood of fire >_<
Without skill being active = common damage
Skill on = class damage, fire for reavers, acid on spiders etc.

Creeps would save a important class trait slot and could swap between dmg types to what suits the opponent your fighting.
At the momen theres classes like spider and warleader with defilers that are bound to their tactical based damage.