Being a guardian beast of Giruvegan, set by the masters of the ancient city to guard the lowermost level against intrusion. Though originally a variety of wyvern, potent Mist has transformed its wings into sharp hook-like protrusions, a shadow of their original size. Its undying loyalty makes the Tyrant a formidable barrier to entry into the ruin's depths.
If the player has the Trident or the Icebrand, it is advised to equip them. The player cannot use Technicks in this battle, so the party cannot steal from the enemy. Use Bubble or Bubble Belt. If one has an overabundance of MP, summon Mateus. However, it is best to save MP for only healing since the Tyrant focuses its attacks on one target at a time. Since the party cannot use Charge, stick with running around the field to gain MP for Raise and Curaja.
When Tyrant's HP falls below 50%, cast Blizzaga to take advantage of its weakness to Ice. It does not have the typical Defense increase bosses usually have, so target its weakness. Note that it has a weakness to Confuse, or at least to Nihopalaoa + Smelling Salts. This can be used to buy time (to heal, buff, etc) if needed.
If the player has a low enough level character, the Accuracy underflow bug can be used to continuously inflict Confuse on it, making the battle trivial.