I think Magician just leaves 10% free at the end by changing the partition size, it does not seem to set a HPA or use DCO. If you started with a secure erase/fa

I think Magician just leaves 10% free at the end by changing the partition size, it does not seem to set a HPA or use DCO. If you started with a secure erase/factory clean SSD, those blocks will be marked as unused and the garbage collection algorithm can play Sokoban with them however it wants.