Mesmerize, Malboro, Vysage, Lefty, Righty
When you reach the Overworld, head east towards the dry lake. Once inside, select a party and move north. In the next area, run up the head of the fossil on the right and follow the path to a Meteor DP. Use it then cross over the bone bridge on the left. Use the Thundaga DP here then continue forward to the edge of the cliff. Choose to jump off.
Head north to the next screen. Once there, move west until you reach a big crevasse. Passing by it wakes up the tenant below.
Weakness: Holy, Heal
Draw: Curaga, Esuna, Dispel, Flare
Abadon is undead so cast Life on it for an instant kill or take time to draw some spells while casting curative magic on it. If you have Leviathan’s Recover ability, use it to inflict 9,999 worth of damage in one shot.
Once Abadon is defeated, head northeast. Examine the strange, electronic barrier in front of you to uncover an opening in mid-air. Climb up to it.