El Gran Terrapín is a fusion of all four Ninja Turtles, created by Yang using the Transmutador Yin-Yang. It is massive in size, comparable to a kaijū, and has a white bandana and joint pads, as well as white eyes. Its belt buckle is the same symbol as the Transmutador Yin-Yang.
El Gran Terrapín was formed to combat the nefarious earth spirit Kurko. He defeats the villain and is restored to all four Turtles by Yin and Yang.
On the cover of El Encuentro de Dos Fuerzas, El Gran Terrapín is shown holding a short sword, but in the story itself, it only fights with fisticuffs and magical blasts.