First Strike is an auto-ability that you can add to your weapons. It is a fairly important ability, especially for certain sections of the game (mentioned below), because it allows the character that has it to act first in battle. The character will be given the first move regardless of the Agility stat or any other effects in battle.

More information about the Omega Ruins can be found here:

This ability is very important for when you are traveling through the Omega Dungeon specifically. This is because the Great Malboros in the area will ambush your party and will use Bad Breath to cause a myriad of negative status effects on your party (that will likely kill your entire party).

First Strike will give you the first attack. If you use Provoke as your first attack it will prevent the Great Malboro from using Bad Breath allowing you to avoid certain death during your travels.

Adding First Strike

You can add First Strike to one of your weapons with a Return Sphere. You can obtain them in a number of different areas including:

• Bribing them from Dark Elements or Mandragoras
• As a reward for defeating Biran, Yenke, the Sanctuary Keeper and Sinspawn Genais
• As a reward for playing Blitzball
• Stolen from a Greater Sphere

Masamune

Note also that Auron’s Celestial Weapon, Masamune, once fully charged, automatically has the First Strike ability attached. Keeping Auron in your party is a good option while traveling through the Omega Ruins.