- 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 first item you are carrying or wearing from the item set you choose is ready to use, meaning you meet its level requirement and it is off cooldown. With Check If Not Carrying ticked, the first item in the set is checked even if you do not have it.
Why you might use it
Check that an item is ready to use: you meet its level requirement and its cooldown is up (or ends with the global cooldown). Add it to steps for potions, Healthstones, explosives and on-use trinkets so they are only suggested when usable; the step's own ownership, usability and range checks still apply. With Check If Not Carrying, the first item in the set is checked as though you had one, which suits a reminder that the Healthstone cooldown is ready so you can get a new one. See also Item Cooldown, Have Item In Bags and Have Item Equipped.
Example
Major Healthstone is available
Settings
What each setting in the condition editor means, from the game's own help.
Item Set - This is a list of items to look for in your inventory. This list is ordered, the top found item in the list that you are carrying or wearing is what will be used in this condition. NOTE: this will NOT search for ANY item in the list that matches this condition, only the first item found will be used in this condition.
You can choose from either a pre-defined Item Set, by picking it by name from the drop down menu. You can edit these using the Item Sets configuration menu. Any item set in cyan is a global item set available to all your characters, otherwise they are available to this character only. If you do not want to set up a reusable item set, you can select Custom to specify an ad-hoc item set.
Edit - Edit the contents of the item set. If you have selected a pre-defined item set, you will be editing that item set, which may affect other usages of that item set (including on your other characters if it is a global item set). An item set must have at least one item in it for this condition to be considered valid.
Item sets are checked in priority order. Bag counts use the first carried candidate, not the sum. Availability, range and cooldown checks use the first carried or equipped candidate. Missing or restricted observations stay unavailable, including under NOT.
Item Available checks the required level and enabled item cooldown. An active cooldown qualifies only when it ends with the readable global cooldown. This condition does not bypass the action's implicit ownership, usability and range checks.
Check If Not Carrying - Check the availability of the first item in the item set as if you were carrying it, even if you are not.