Like its cousin, the Tonberry, Master Tonberry counters all forms of damage with Traveler. The Master Tonberry can use Barrier Change to change its elemental weakness. Players can figure out to which element it is weak from the spell it casts; it always casts a spell of the "opposite" element to which it is weak:
The Master Tonberry starts out with a physical attack, then begins taking steps towards the party once every fifteen seconds. Each time it takes a step, it uses Barrier Change to change its weakness. After seven steps, it uses the dreaded Knife attack on a party member, which deals damage equivalent to fourteen physical attacks. It then retreats halfway and starts using Knife every four steps. It is vulnerable to Sleep.
The Master Tonberry drops the Gladius, a powerful Holy-elemental dagger, when defeated.
Sleep can be used to slow it down, but all attacks dealt to it while asleep must be magical (so it does not wake up) and non-elemental (so it does not get healed). Flare fits this job nicely, as Grand Delta and Ultima do.
If weak to Ice: Firaga (66%) or Nothing (33%)
If weak to Fire: Blizzaga (66%) or Nothing (33%)
If weak to Wind: Thundaga (66%) or Nothing (33%)
If weak to Holy: Bio (66%) or Nothing (33%)
If weak to Lightning: Tornado (66%) or Nothing (33%)
If weak to Poison: Holy (66%) or Nothing (33%)
If weak to Water: Quake (66%) or Nothing (33%)
If weak to Earth: Tsunami (66%) or Nothing (33%)
If Timer >= 15:
Set Timer = 0
Monster flashes and moves a little closer to Characters