Mana
Mana is the magical energy used by characters in the Diablo games to cast spells or use skills.
Background
Mana is what the primal arcane magical force that pervades Sanctuary is usually called. Individuals skilled in sensing this power can channel the spiritual essence stored in their bodies through different techniques in order to accomplish great feats that they would be physically incapable of doing.
Mana Attribute
In Diablo 3, Mana will not be used by all classes. The Barbarian, for instance, uses Fury instead to make more sense with the world lore and gameplay mechanics. No specific Attribute has been increasing the Mana pool of a character in the demos of BlizzCon 2008 and BlizzCon 2009, but Vitality increased Mana regeneration.
Mana regenerates very slowly and characters who use Mana will have to rely on skills that enables Health Globes to give back a portion of mana as well and any other skill at their disposal to increase their reserves.
Development
In the first gameplay video from WWI 2008, the Barbarian did actually use mana as a resource pool. The D3 Team mentioned at BlizzCon 2009 that more of the classes will use a non-traditional resource pool, which means the Monk, Witch Doctor or Wizard might get alternate skill mechanics as well.
22nd of September 2009, Bashiok announced the Wizard will not be using traditional Mana, but a resource more specialised for the class. [1]. This was later confirmed on 6th of January 2010[2], when the name of the resource was released: Instability.
On 6th of January 2010, it was also revealed that work had begun in earnest to design the Monk's resource pool.[3]
