- Not available on that edition (the reason is in the tooltip)
- Depends on the setting, your class or another addon (details in the tooltip)
What it does
Checks how much mana the unit specified has as a percentage of its maximum mana, compared with the percentage you set.
Why you might use it
Compare a unit's mana as a percentage of its maximum. Common uses are Evocation, Innervate or a mana potion when you fall under 20%, dropping expensive spells below 30% to conserve mana, or on a target, aiming Viper Sting or Drain Mana at casters that still have mana. Not available on Retail or Forever, where the game hides mana values from addons. See also Mana and Mana Percentage Within Range.
Example
your mana is less than 20%
Settings
What each setting in the condition editor means, from the game's own help.
Unit - The unit this condition uses as the target of comparison.
Operator - How to compare Mana Percentage with the Mana value. This comparison uses basic mathematical comparison operations.
Mana - The mana value of Unit as a percentage of their total mana.