rankx using column of variable table

You can, your syntax is off just a bit though felipefrutuoso 

When you create a table using a variable, if the function can see the table (iterators can, aggregators cannot), the field name has to be wrapped in square brackets.

EVALUATE
VAR myvirtuatable =
    ADDCOLUMNS(
        SUMMARIZE(
            FILTER(
                'table_a',
                [field] = 666
            ),
            'table_a'[field2],
            'table_a'[field3]
        ),
        "total",
            CALCULATE(
                SUM( 'table_a'[value] )
            )
    )
VAR Result = 

    ADDCOLUMNS(
        myvirtuatable,
        "RANK",
            RANKX(
                myvirtuatable,
                [total],   <---- Adjustment to syntax
                ,
                DESC
            )
    )
RETURN
	Result

See if that works for you.