Mana

Mana is a magical power resource available to casters which they draw upon when casting spells. It has some parallels with the warrior's rage, the rogue's energy, and the hunter pet's focus. The amount of mana currently available to the caster is denoted with a special blue mana bar below their health bar. By default, casters start with a full bar of mana which is then depleted as they cast spells.

Characters have an innate replenishment of both health and mana. The rate at which mana replenishes (mana regeneration) is based on the Spirit attribute. Some Talents can raise the replenishment rate for these stats independently. Mana regeneration in combat is much reduced, but some mana can be replenished instantly during combat using mana potions from alchemists or from various magical items. Out of combat, mana regeneration can be increased significantly by using various drinks. Mana regeneration can also be increased through the use of certain buffs.

The maximum amount of mana available to a caster is determined by a combination of the character's class, level and their intellect. As for Gems, Red gems can grant bonuses to intellect while Blue can increase your spirit. Finally, items can be enchanted to give additional increases to mana.

Base mana is a term used to refer how much mana a character has before it is modified by intellect and other item effects. Many spells require a percentage of your base mana to be cast. Mana pool refers to the total amount of mana a player possesses, disregarding any increasing or decreasing effects (though it usually refers to the sum of increasing).

When out of mana, /oom issues a verbal comment to others around stating that you are out of mana or low on mana. You can also just use "OOM", "oom", "LOM", or "lom" in chat.

Mana Formula
A player's Mana pool is mainly determined by their Base Mana and their intellligence (not counting any mana increasing effects or items):

MaxMana = BaseMana + ManaFromIntellect = BaseMana + ( min(20, Int) + 15*(Int - min(20, Int) )        = BaseMana + (20 + (15*(Int – 20))       //for Intellect 20 or over = BaseMana + (Int)                      //for Intellect under 20

Example: Level 48 Human Mage

MaxMana = BaseMana + ManaFromIntellect = 1021    + 20 + (15 * (Int-20)) = 1021    + 20 + (15 * (220-20))         = 1021     + 20 + (15 * (200))         = 1021     + 20 + (3000)         = 1021     + 3020         = 4041