Here is the full list of all 9 Ophidia achievements.
Stay alive in the Underworld for 120 seconds.
Stay alive in the Fire World for 120 seconds.
Stay alive in the Ice World for 120 seconds.
Stay alive in Heaven for 120 seconds.
Consume the giant beetle in the Underworld.
Consume the giant salamander in the Fire World.
Consume the giant whale in the Ice World.
Consume the thunderbird in Heaven.
Conquer each world by consuming the boss in the center.