Mana

Mana, also called MP, is the magical power a caster spends to work tier spells in Overlord, both inside the game YGGDRASIL and out in the New World,; it fuels runecraft too. The supply is finite, so timing matters: spending it freely early leaves nothing for a long fight, and a spell broken off by interference burns the cost without producing anything. Warrior-mages are the most exposed to that, since even a small disruption breaks their concentration. Running dry brings ragged breathing, then immobility, and finally unconsciousness, and the only cure is rest, meditation or sleep. In YGGDRASIL a full recovery takes six hours and a character's base pool is ten times their level; in the New World it can take the better part of a day. Casters who are empty fall back on scrolls and wands, since magic items hold mana of their own, and how much an item holds is a fair measure of its power.