Zombone

Zombone is the skeletal counterpart and second form of the Czar Dragon. After the fomer's defeat at the hand's of Mario and his party, he falls and becomes submerged in the lava underneath him, which brings about the form of Zombone.

While Zombone has stronger attacks than the Czar Dragon, he has less defense. He is also vulnerable to thunder attacks. He no longer has the power to use fire attacks or summon Helios either.

Trivia

 * Czar Dragon's death and re-birth as Zombone is similar to Bowser's death and return as a Dry Bones-like creature in New Super Mario Bros.