Chong po gong fu cheng (1979)

Those who enter the castle of Ching never return. Forced into slavery, every day becomes a punishing ritual down the Castle's secret gold mine. One worker, Kang, decides enough is enough, and tries but fails to abate the oppressive master Ching. For his efforts, and as a warning to others, Kang's hands are smashed, foiling any more attempts at rebellion. But Kang's determination to destroy the Castle and its keepers only increases, though with two useless hands he is left with just one chance - to learn the 'Heaven Legs' technique and face Ching in one last neck-breaking battle.