- 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 game offers Blizzard's Assisted Combat for your character and current specialization. When it is not offered, the condition is false rather than unavailable.
Why you might use it
Matches when the game offers Blizzard's Assisted Combat for your character and current specialization. Use it at the top of a branch to follow Assisted Combat where Blizzard has a rotation for your spec, and fall back to your own steps where it does not. Assisted Combat is a Retail feature; on a client without the Assisted Combat API this condition is unavailable rather than simply false. See also Assisted Combat Suggestion.
Example
Assisted Combat is available
Settings
What each setting in the condition editor means, from the game's own help.
Matches when the game offers Blizzard's Assisted Combat for your character and current specialization. When it does not (for example a specialization Blizzard has no Assisted Combat rotation for, or a client that declares the API but does not offer the feature), this is false, so a branch can fall back to your own steps.
Unavailable only where the client has no Assisted Combat API or its answer cannot be read, including under NOT.