Lost Odyssey

The final battle is a easy one, which was a disappointment. Well, it was easy for me since i was level 79 (immortals). You cant use your mortals in the fight, but they do help out, all 5 mortals cast a different spell to aid you in the first of the last 2 battles. In the very last battle, all you gotta do is take around 50k hp from him, but dont waste your time casting Buff spells (spells that add strengths to your party like barricade, or powerus type spells) so just stick to damage dealers. I would suggest casting double-leveler with sarah and ming, and attacking normally with kaim and seth. OR you could attack with kaim and seth, and cast Zephyrus-Divide (not the other way around, make zephyrus first) with both sarah and ming. The reason you cast zephyrus first is because it will allow you to cast divide without waiting a turn. Double-cast skill is needed of course. When the battle is over, there is like 15 minutes of cutscenes. I wont spoil it here, but it is a great ending. When the credits come, skip em, youll get the achievement, and youll be asked to save your game. SAVE! it will allow you to start a new game from disk one (on the save that your using) with level 50 characters, but nothing else. This is extremely helpful, especially if your gunna run through a second time in order to get the treasure trove. Refer to my treasure trove solution for help. If you need a step by step guide to treasure trove instead of just a list of items in each area, go to gamefaqs, and find lost odyssey, then read Split Infinity's lost odyssey guide. Follow it by the letter and youll get the treasure trove achievement.

To even reach disc 4 in the game, you've mastered the art of ring-usage and battle formations.
You've also done your fair share of grinding each area.

Since we've established that, all there is left for you to do now is finish off all the sidequests (Each give you a fair amount of levels, and the ever-important Element absorbers!) and level up a bit in the Temple of Enlightment.

Level 70+ will suffice for the final battle, and it is recommended you have the Orichalum weapon for Seth and Age of the Kings for Kaim. (Tolten side quest reward)

With those requirements, the final battle is a breeze.

The only other difficult part would be the Arthrosaurus battles in the sea; For those, the sleep spell is a must. Casting sleep and moving onto another one DOES work. Remember to check the elements for each, the damage increase is substantial. (That goes for EVERYTHING)

Jansen's final skill *double cast* is a useful asset, as is Sed's 3 accessories.