Loki Headcanon:
His eyes start turning green when using his powers to the limit.
Not just his eyes, but his veins glow green too.
In fact, after becoming more comfortable with his Jotun side, the glow follows his markings, even if he's in his Asgardian form.
However, if his eyes become completely green, he's about to reach his limit.
Once the limit is reached, any illusions he has will fall.
However, it also leaves physical damage.
He collapses, and his body grows comatose.
But his magic will still protect him against any threats, real or perceived.
Because while the mage controls the magic, letting it flow through their veins until it bonds to every cell in the mage's body-
It still is somewhat sentient.
Sometimes, the magic will shut down the mage's body for its safety or for the safety of the mage
If a mage's body can no longer hold the magic
There's a risk of what is akin to a radiation leak.
Depending on whether it's an expulsion of the magic, or death of the mage will determine if the "leak" will leave behind a
Blessing,
Or a curse.
