Pelennor Fields

Upon the beast sat a shape, black-mantled, huge and threatening. A crown of steel he bore, but between rim and robe naught was there to see, save only a deadly gleam of eyes: the Lord of the Nazgul.

Normal sudoku rules apply.

Values in cages must sum to the given total.

Nine cells on the battlefield (grid) are 'Nazgul' cells -- the digits 1 to 9 once each -- one in every row, column and box. The value of a Nazgul cell is DOUBLE the digit it contains. Additionally, no Nazgul is a (chess) knight's move away from another Nazgul, and no cell a knight's move away from a Nazgul can contain the same digit.

The locations of the Nazgul are to be determined by the solver.