Amputate

Amputate is the most used technique of Trafalgar Law once inside the ROOM. As the name suggests, it allows Law to cut through things with his cursed sword, known as Kikoku.

However, the things that he cuts through can be reattached, and in the case of people, they don't feel any pain when Law unleashes this technique on them. It is strong enough to cut through mountain ranges, depending upon how big Law's ROOM is. It is also implied to be able to tear through Haki.