I think cold MT needs some love, and not another high damage ranged attack like it already has, plus cold damage in itself needs more attention.
Endothermic Aura makes the air all around the caster to drastically drop in temperature to sub-zero levels, releasing clouds of cold air (Cryogas), at the first turn the cloud is small, at 3x3 radious, but after that, the cloud grows in size to 5x5 radious.
Any enemy that walks into the cloud will suffer cold damage depending on the caster's MT skill, upon first entering in contact with the clouds, the target will be chilled, and 2 stacks of chilled will be applied per turn if remains inside, on second and third turns inside cloud, Hypothermia will be applied, and in the fourth turn inside the cold clouds, enemies will be frozen.
Endothermic Aura freeze can be boosted by Cryokinetic induction, causing the enemy units to shatter.
Cold clouds dissipate at a normal gas speed.