Drain, Aero, Pain
Armadodo, Bomb, Buel, Blobra, Forbidden, Red Bat, Tonberry
Travel to the upper half of the Centra region and look for a yellow, diamond-shaped structure on the southeastern island within a ring of smaller islands near the Centra Crater. It might take a while to find the ruins, so use your map.
Once inside, you’ll have exactly 20 minutes to find Odin and defeat him, so come prepared with Diablos’ Encounter Half or Encounter None ability. If you happen to face any enemies, use your most powerful spells or Squall’s Renokuzen to kill them quickly (GFs take too long).
From the entrance, head north and ascend the stairs. Use the Drain DP on the right then move clockwise around the circular statue and climb the stairs behind. On top, take the right path and go all the way to the door in the background. Climb the stone steps to get to the lift platform.
On top, take the left ladder to the top and enter the opening. Activate the switch. Climb back down and examine the blue altar to reveal a new staircase on the right. Climb the new staircase (not ladder), spiraling up until you reach a circular platform. Climb the short ladder on the left. Head right and pluck the red jewel from the eye of the statue. Return to the circular platform below.
Take the upper right path to a Pain DP. Climb up the green dome to reach another statue. Put the jewel in to obtain a random 5-digit password. Write it down then take out both red jewels. Return to previous statue and insert both jewels. Enter the 5-digit password. When the door opens below, enter it to face Odin. [Note: If the timer runs out before you face Odin, you’ll be asked to try again. If this happens, just continue from wherever you left off. If the timer runs out during battle with Odin, it’s Game Over.]
Draw: Stop, Death, Double, Triple
Odin will just sit there until the timer runs out, so your goal is to hit him with your most powerful stuff as quickly as possible. The easiest way to defeat him is to use Squall’s Limit Break repeatedly. No spells or GFs work as well as Renokuzen. Stock up on a few Triple spells if you’ve got time and make sure to mug a Luck-J scroll from him.
Unlike regular GFs, Odin cannot be junctioned; rather, he appears randomly during enemy encounters. When he does, he’ll instantly dispatch all opponents with a success rate of 100%. Don’t expect him to come help during boss battles, though. Once you obtain Odin, use the ladder to the right of the blue statue to reach an Aero DP then exit the ruins.