Metal Knack is a variant of the original knack. In Knack 2 after reaching the mines, metal knack makes its first appearance.
As knack is a variant of the original, metal knack will have special powers. pressing square will render a metal punch to your opponents. Holding down square will unleash metal whip, which is a temporary replacement for multi-punch. Also, as long as knack has metal on his body, he will be invulnerable to attacks. The more Iron you have, the more shield you will have. Also during metal knack, there are circuits you have to acctivate with electricity. Starting from the circle that has electricity, holding down R1 while running to the un-electricified circle and releasing it there will complete the circuit.