One: Piece Episode 371

In , the "useful feature" refers to Gecko Moria's ability called Shadow Revolution . Shadow Revolution: Moria’s Manipulative Power

During the battle against the Straw Hat Pirates, Moria demonstrates that by manipulating a person's shadow, he can force their physical body to change its shape as well. One Piece Episode 371

Moria also uses a useful defensive feature of his Shadow-Shadow Fruit powers to instantly switch places with his shadow, Doppelman , allowing him to evade attacks—such as when he rendered Nico Robin's Clutch attack useless by swapping locations with his shadow. Episode Overview In , the "useful feature" refers to Gecko