El Martillo

is a technique used by the Hollow, Ayon.

Description
Ayon's right arm rapidly enlarges in size to more than double its original thickness, bringing with it a proportionate increase in the arm's mass and, as a result, a drastic rise in its destructive power. When used against Genryūsai Shigekuni Yamamoto, Ayon only resorted to the technique once enraged after being injured, but the subsequent attack failed to connect, due to the Captain-Commander's proficiency in Shunpo.