The evolution began with a boom. Gravis' body had way too much lightning, which all went into his body and Spirit now, boosting them way past the requirements for the evolution.
Gravis felt the evolution and felt his body changing. In no time at all, Gravis imagined the picture of the body he wanted to create. This time, in comparison to all the previous evolutions, he wouldn't change much. All aspects of his body had already been covered, and making big additional changes would ruin his body's balance.
Gravis' body shook as he began to become smaller again. He hated it that he always continued growing with each level up inside the Realms. Such a big body might be useful against beasts since they were even more massive, but in the future, when he met humans again, such a huge body would only be a liability.