- 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 if the spell you choose is active or pending, such as being cast right now or queued for your next swing.
Why you might use it
Tells whether a spell is currently active or queued, which matters most for on-next-swing attacks: do not suggest Heroic Strike, Cleave, Maul or Raptor Strike again when it is already queued. It also helps with toggled or channeled abilities that should not be pressed twice. See also Spell Auto-Repeat Active for Auto Shot and wands.
Example
Heroic Strike is active or pending
Settings
What each setting in the condition editor means, from the game's own help.
The icon next to the spell name will automatically update to display the spell that is currently selected. You can drag a new spell from your spell book or action bars into this icon slot to replace your selected spell.
Use this exact spell rank - Unticked (the default), any rank of the spell matches. Ticked, only the rank you chose matches. (only on Classic Era, TBC Anniversary, Forever)
Spell - This is a specific spell used in this condition. You may drag this spell from your spell book or action bars into the input field or spell icon to set this value. This input field has prediction enabled, so you do not have to type the full spell name, just select from the prediction frame when it appears.