PowerType

Many of the API functions which are used to gather information about a unit in the game world (Players, NPC's, Monsters, etc) will return information about types of powers that various units use as a basis for using abilities.

Constants
These are found in FrameXML\Constants.lua.


 * SPELL_POWER_MANA = 0 : Mana will range from 0 to the maximum mana a unit has. Player mana pools are calculated based on a base mana pool plus a certain amount given by the Intellect stat.  This is the default power type for most non-player units, although there are exceptions.


 * SPELL_POWER_RAGE = 1 : Rage is used by Warriors and Druids in bear form. Rage goes from 0 to 100, but may be increased via player talents.  Rage degenerates back to 0 out of combat.
 * SPELL_POWER_FOCUS = 2 : Focus is used by Hunters and hunter pets. Focus goes from 0 to 100, and has a slow regeneration rate, but certain abilities will generate focus.
 * SPELL_POWER_ENERGY = 3 : Energy is used by Rogues and Druids in cat form. Energy goes from 0 to 100, but may be increased via player talents.
 * SPELL_POWER_HAPPINESS = 4 : Happiness goes from 0 to 100, is used by hunter pets, and affects their damage output. Happiness can be increased by the spells Mend Pet or Feed Pet via a minor glyph.
 * SPELL_POWER_RUNES = 5 : Runes are used as a power type for Death Knights. By default, they have 6 runes (1 & 2 are blood, 3 & 4 are frost, 5 & 6 are unholy), but certain talents and abilities may change the type of a rune.  Runes can be converted into a Death Rune, which can be used as any other type of rune.
 * SPELL_POWER_RUNIC_POWER = 6 : Runic power is used by Death Knights. It is gained via certain abilities, and does not degenerate out of combat.
 * SPELL_POWER_SOUL_SHARDS = 7 : Soul Shards are collected by Warlocks, and range from 0 to 3 indicating how many are available. Soul Shards do not degenerate out of combat.
 * SPELL_POWER_ECLIPSE = 8 : Eclipse is used by Druids in moonkin form. Eclipse power goes from -100 to 100, and its use as solar or lunar power is determined by what buff is active on the player. Buffs activate at -100 and 11 respectively and remain on the player until the power crosses the 0 threshold.
 * SPELL_POWER_HOLY_POWER = 9 : Holy power is used by Paladins.
 * ALTERNATE_POWER_INDEX = 10 : New power type since Cataclysm. Known uses: sound level on Atramedes, corruption level on Cho'gall, consumption level while in Iso'rath.

Others
There are two other types, AMMOSLOT and FUEL, as returned by UnitPowerType. These are used by vehicles, but do not appear to have a constant associated with them.