Here are some places you might see in the Holy Isle of Neos in Dragon Quest VIII.
Altar of Naraku is a sub-event dungeon added in the 3DS version of Dragon Quest VIII. Note that since it has nothing to do with the story, you may choose to visit later to clear the dungeon. You should finish the Dark Magic City of the main quest first before proceeding.
Proceed to the trial in the deepest part. Investigate the crystal ball.
After this, go to the altar of Naraka near the wilderness ship’s location.
Altar of Nakaru
First Floor: Go up the ladder at the corner of the room. Operate the switch for the stairs to descend from the ceiling. In the room on the lower side, push the switch and turn all three images towards the opposite direction to the stone plate. The stairs will appear.
Basement 1: Collect items in front of the stairs to B2 gatekeeper. After that, get ready for combat. You’ll encounter a Gatekeeper of Heaven.
Boss HP is 850. It only has one normal attack with one action. It has a very high attack power, so improving your defense will make this battle easier.
The boss drops the seeds of skill.
Basement 2: This swamp takes 5 hp. Make sure you pay attention to your HP as you go through this area. You’ll encounter Jahagaros in his first form.
We recommend you fight this boss at least around level 40, since the boss’s HP is around 2400. Take note that when you defeat the beast for the first time, it re-emerges in its second form. Remember to conserve MP!
The monster uses regular attacks in the first form. One blow, one injury (four times), and Bagu cross (one whole).
Normal attacks take around 100 for standalone attacks, taking 100 HP for random attacks up to four times.
When Jahagaros attacks, his blows aren’t so high, but you might meet instant death.
Make sure you raise your defense to keep your HP high. This is crucial if you want to survive the fight.
Jahagaros’s second form has about 4800 in health. You should use regular attacks, islands (4 times), huge rocks (whole) and bagacros (whole).
Jahagaros’s normal attack damage will increase to about 150. Bagiskuros and Isuma will deal the same damage as in the first form. For huge rocks, the enemy will deal 150 damage in total.
When defeated, the monster drops an anti-friction cough.
Click here for a more detailed guide on how to defeat Jahagaros which includes the boss’ stats, attacks, behavior, and recommended equipment to use in Dragon Quest VIII on the 3DS!