The deadly drawback of using too much magical potential carelessly.
Prevalence: very rare (1:10,000)
Lethality: highly dangerous (lethal if continued)
Description
When you use too much magical potential, the energy flowing through the magicampal pathway damages the surrounding tissues, first leading to a small nosebleed, but quickly escalating if continued carelessly.
Luckily, most people will never get to the stage where their nose starts bleeding, instead passing out if they use too much magical potential.
Symptoms
If after the initial nosebleed, you continue to use magic, eventually, the amount of damage to the brain causes instant death (often because either the heart or breathing stops).
Misc
Countless warriors have died from overusing magic in battle, causing their breathing or hearts to stop.
The World Stones 