Golden Sun: The Lost Age - Sentinel (Optional) Boss Battle

If you thought Valukar was hard, wait 'til you encounter Sentinel, the guardian of the Catastrophe summon tablet. Sentinel lives within the depths of Sea of Time Islet which is only accessible when you complete the trading quest (side quest). The turtle will give you a ride to this location by mind reading. Nothing special can be found in this cave other then a few minor treasures. Once you get the Teleport psynergy, you will be able to access the hidden realms of Islet. Along the way, I decided to hunt for Tisiphone Edge which is a great addition as a weapon. Sentinel was not an easy enemy due to its frequent uses of stat boosters. His armor is also non-deductible which means that you cannot restore his stats back to normal by using Break, so don't attempt to do it! Sentinel can easily take down your defense with Armor Crush, but that's about it. You may wish to use summons to take him down easily, but for those who want to have a challenge can always follow my battle style (although not preferred since this battle took forever). My party was early in its 50s (probably 51-53). No summons and djinn were used, and only physical attacks were used. This battle is long, tedious, and redundant, so if you want to skip some of the repetitive actions, you may do so (in fact I suggest that you do xD).