Final Fantasy screenshot

Final Fantasy X - Omega Ruins

Although the Omega Ruins is hard to beat, it has valuable things, and in a way it has new interesting story elements.

Go to your airship and select the option "Omega Ruins". Your goal in the Omega Ruins is to defeat and release the soul of the heretic "Omega". Another reason to come here is for the items, as every monster drops a level 3 or 4 key sphere. The bad part about the Omega Ruins is that you will uncover the map slowly as you walk around.

From the entrance move to the west corridor. Follow the path up to a doormat glyph on the wall. Head north from there to find a chamber with 4 chests. The Al Bhed Primer (last volume) is on the floor north of these chests. Head northwest from this room into a side corridor with another glyph. Activate this one and return to the "doormat" one. The glyph is now working and it raises a bridge out to a chest suspended above the central spage. Collect the teleport sphere. Now, at the north end of the ruins is a teleport pad. It will take you to a chamber where the party encounters a monster called the "Ultima Weapon".

Ultima Weapon

Boss: Ultima Weapon
HP: ???
Steal: Door Way To Tomorrow x10
Boss Battle Tactic/Solution:
Before beginning the battle, equip armor that protects against status ailments like confusion, petrify, and silence. Try to inflict silence and dark to hinder Ultima Weapon's magic and regular attacks. You can bribe him with 1,400,000 Gil and get 99 Pendulums. But, just stick to the fighting.
Once Ultima Weapon is defeated, you'll realize that it was only a shadow of the Omega Weapon and step on the teleport pad to proceed. Once you arrive at the upper level, you'll be forced to fight a few monsters. HERE is the trick. First head left to the dead end. You will fight 2 monsters along the way. Then head back to the right and work your way around. This will make you encounter 10 monsters which is exactly what you needed in order to fight Omega Weapon! Now go in and fight him!

Omega Weapon

Boss: Omega Weapon
HP: ???
Boss Battle Tactic/Solution:
Since Omega Weapon is pretty much immune to everything it's a good idea to focus on your own defense. Use shell, haste, focus, and other abilities to make sure you actually stand a chance. Kimahri can also Lancet to acquire the ability, Nova from this boss. Other than that, do your best to beat him.