- 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 the level of your active Mythic+ keystone compares with the number you set. It is 0 when you are not in a Mythic+ dungeon.
Why you might use it
Change the rotation by how hard the run is, for example holding cooldowns for bosses in a high key. The level is 0 whenever you are not in a Mythic+ run, so "at least 10" is only true inside a run of that level. Retail only. See also Instance.
Example
the level of your active Mythic+ keystone is greater than or equal to 10
Settings
What each setting in the condition editor means, from the game's own help.
The level of the Mythic+ keystone you are running. It is 0 whenever you are not in a Mythic+ dungeon, so 'at least 10' is only true inside a run of that level. Retail only.
Operator - How to compare Mythic+ Keystone Level with the Level value. This comparison uses basic mathematical comparison operations.
Level - The keystone level of the Mythic+ dungeon you are running; 0 when you are not in one.