It is so massive it can pick up a rancor with one hand and still have room for more in the same hand. Starkiller's lightning did damage to it, but the thing is so large that it does more damage to itself when it accidentally hits itself when pissed off with Starkiller for restraining it in the arena twice. It's also insanely strong, because both times after Starkiller restrained it, it broke out, then it tore off supports for Cato Nemoidia's Coliseum like they were no more than paper. If it hadn't caused the Coliseum to fall off the rest of the city, grabbing Kota on the way down, Starkiller wouldn't have beaten it, because the Gorog landed among Cato Nemoidia's mountains when it fell. So there is the answer to your question and a little more. Sorry about the bad post above, using iPhone and my finger bumped the "submit reply" button.