Michael was too focused on the Curse and trying to find its true agenda, and he was too late to move when more bony hands emerged around his feet.
He tried to evade them, which mainly worked fine. The only problem was that one of the bony hands managed to scratch his calf. The scratch wasn't too bad since the bony hand barely managed to get through his skin, but the problem was that a trace of corrupted darkness entered Michael's body.
He used True Extraction right away to remove the corrupted darkness. Unfortunately, that didn't work as expected. He could temporarily contain the corrupted darkness and move it around as he pleased, but it was impossible to extract the corrupted darkness without inflicting harm on himself.