Magical Burnout

A potentially deadly mistake can be made by using too much magical energy in a short time. To do so can overload the magical pathways to the extend of severe burns or even spontaneous self-combustion.

Causes

Massive amounts of magic rushing through the bodies magical pathways result in those pathways heating up significantly, this increases body temperature along the pathways.

In game terms that means whenever a certain percentage of the users magical potential is used you need a check. I suggest a constitution check with a DC of 15 for D&D and with a modifier of -3 for TDE.
What does it mean, too much magic channelled? Well, my suggestion is for TDE to say 50% of the basic maximum ASP value used in one action. And for D&D sum up all Spell-slot levels and if the user spends 50% of that number in one turn or two consecutive turns the roll is needed. [be] Increase the difficulty for the con check by one per spell slot over 50% or by one per 5 ASP over the 50% mark.

Symptoms

In effect, the pathways can become so hot, that the body suffers the symptoms of burns from sunburn to massive blistering or even charring. In very severe cases parts of the body could ignite and, in an extreme case, so could the whole body.

In the game treat this like damage from fire spells or if your game has the rules as burns of 1st to 3rd degree.

Type

Magical