Things You'll Need
Instructions
Choose which three characters you want to use Judge Ghis. It does not matter which characters you choose.
Learn one Quickening attack on the License board for each of these characters. It costs 50 license points to learn this ability.
Use ethers to completely fill the MP bar for all three characters. The bar should now be gold. This indicates the character can use her Quickening attack. This is the fastest method to prepare to fight Judge Ghis.
Fight random encounter enemies to recharge your MP if you have the Headsman or Inquisitor augment. Headsman gives you MP for killing enemies. Inquisitor gives you MP for damaging enemies. Augments are always active after you learn them and do not require using a specific skill to gain the benefit. This is the quickest method for charging MP if you do not have ethers.
Walk around in circles to restore your MP. This is by far the slowest method to regain MP, but does not require you have any augments or items.
Enter the Port Launch room of the Dreadnought Leviathan to start the battle against Judge Ghis. Have all three characters use their Quickening attacks at the start of the fight against him. Between the Quickening damage and the damage caused by Inferno, Judge Ghis should be dead or very close. If he is not dead, it should take only a few normal attacks to defeat him.