Sample page using variables: http://tales-of-link.wikia.com/wiki/%28Artes_Wand_User%29_Agria
Topic on Extension talk:Variables
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That's not supported by the extension. You'd need to write a new extension on top of Variables to achieve this but it's not impossible.
It's an interesting thought to save the distinct var_final values in page_props to make it queryable… Maybe I will put some effort in implementing this additional functionality at some point in the future.
This is tracked in T191575.