To enter the Moon Island forest and reach the dungeon, you will need 2 Kokoko Nuts.
To get to Moon Island, see this article. But first, I recommend doing the quest "Tas les boules", which is picked up at the Amakna Smiths' workshop at [-1,2] from Hanniboul Smisse. This will let you earn the "Flower" emote at the end of the dungeon.
In the forest there are small stone steles made up of several balls, which tell you the number of Kokoko nuts needed to move on to the next map (shown at (1) in the screenshot). To enter the forest, click on the spot marked by the arrow (2).
Monsters
Kanniball Jav
Kanniboul Jav
Lvl 53 to 61
Kanniball Thierry
Kanniboul Thierry
Lvl 53 to 61
Kanniball Sarbak
Kanniboul Sarbak
Lvl 53 to 61
Kanniball Archer
Kanniboul Archer
Lvl 53 to 61
Haloperi Doll
Poupรฉe Aycetroy
Lvl 52 to 60
Rooms
Room 1
Room 2
Room 3
Boss
Kanniball Andchain โ
Kanniboul Ebil
Lvl 60
Dungeon mechanics
The Kanniball Andchain summons a Haloperi Doll.
You will need to kill it first, since it absorbs the damage dealt to the Kanniball Andchain. To complete the "First" achievement, you will have to kill the boss with indirect damage (pushback, poison...).
Achievements
End of the dungeon
Well done! To leave, talk to the Kind Kanniball Organizer. If you had completed the earlier steps of the quest "T'as les boules", you will receive the "Flowers" emote.