In Mission 16, after you defeat Griffon, return to the Coliseum to find this secret mission.


Several Sargasso will be conveniently arranged in a staircase type pattern and, most importantly, will not attack you on Normal or lower difficulty. You have to jump up their heads to the top. It may take a few tries, but you'll get there with patience.

If you find yourself overshooting the orb by using the last skull, air raid may be of assistance.