- 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 whether the unit specified is the kind of mob that runs away at low health. It relies on MobInfo2 records, so a mob you have never fought does not match.
Why you might use it
Predicts whether a unit tends to flee at low health, so you can slow or root it before it runs: Hamstring for a Warrior, Wing Clip for a Hunter, Frost Nova for a Mage, often paired with Health Percentage. The prediction comes from the MobInfo2 addon, which learns it from past fights with that kind of mob; it can be wrong, and it stays false until you have met the mob at least once. Without MobInfo2 installed it does nothing. On Retail and WoW Forever it is unavailable when the game hides the unit's name.
Example
your target will run
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.
This condition uses data from the MobInfo2 addon. As such it relies on previous interactions with the type of mob in question, which may be inaccurate. Additionally, until you encounter the mob at least once, this condition will always be false.