Mana starvation

Running on empty.

When a being runs completely out of mana, they begin to suffer from mana starvation. If they go without mana for a prolonged period of time, the condition can quickly become life-threatening. For the opposite condition, see mana inundation.

Causes

When a spellcaster uses all of their mana, they will be fine as long as they stop casting spells. But if they keep on using mana at the rate they're taking it in, mana starvation will set it. These cases are usually minor, as people generally only do this for a few minutes at most, and manage to keep most of their important cells. And even if they're particularly stubborn, the caster will likely pass out before enough damage is done to their body to kill them.
More serious cases come from malicious spells such as siphon, which actively drain the target's mana, or bind core, which prevent the target from absorbing mana. Spells like these can prevent the victim from replenishing their mana, which can cause mana starvation to continue for potentially lethal amounts of time.
If someone enters the essential plane, all mana will instantly be taken from their body, and mana starvation will set in quickly enough to kill them in a matter of milliseconds. However, this is by far the least common instance of the condition.

Symptoms

All matter is imbued with mana, and all living things require mana to live. To supplement a deficit, the body will drain the mana from itself and pour it into the core. If this goes on for too long, the body will start to decay until it can no longer function. Damage from mana starvation can be healed naturally over time if it's minor, or through the use of ncecrotic spells if it was a more severe case. However, after surviving it once, repeated instances of mana starvation will take more and more of a toll on the body.

Treatment

As long as nothing is actively draining someone's mana or blocking their absorption, the condition should go away on its own as the patient absorbs mana from the environment into their core. Certain holy spells such as restore can accelerate the process; though if the patient can't absorb mana on their own for some reason, such spells may be necessary to save them.

Type

Magical

Rarity

Common