"Create a party with friends and conquer the two-floor underground cave. This is a multiplayer dungeon. At least 2 players are required to complete dungeon."
Suggested: Lv2-3 / Reward: Jeweled Chest Lv5
As soon as you start the mission, use the Don Don Chaka Chaka song to break the floating blocks above you to get a Treasure Chest and a key, which will be useful later. This is easiest to get if you are a Taterazay or Tondenga, as they positioned right underneath the block supporting the chest.
Walk forwards until you reach an Iron door with a pressure pad on each side. Have one player stand on a switch to have the door sink into the ground so you can pass. Once a player is off the switch, the door will rise up again, so be aware of this.
A few feet past this spot is a large boulder with a Cyclops behind it. Destroy them and move on to find the same setup, except some Kibadeth and Yarideths are helping the cyclops battle you, and a Bonedeth fortress lies behind them. Once you take out these enemies, keep walking and you'll find that yet another Bonedoor blocks your path, but this one has a boulder on the first pressure pad. Pass it the same way you did before, and break the boulder.
Another boulder with a Cyclops behind it lies ahead, but past that are some more Kibadeth, and a large boulder. Destroy them, and the Cyclops and Bonedeth that lie behind them. Break the last two boulders on this floor, and proceed to a demonic padlock. If you have the key, the door will unlock and disappear, but if you don't have it you must restart the mission. Next time you play the mission, if you unlocked the door before, it will be replaced instead with a Strongdoor that can be broken down by your attacks. Pass the goal and you will be given a choice to proceed to B2, or to retreat and keep the treasure you have found so far.
"Face the giant dragon lurking in the final co-op stage."
Suggested: Level 3 or higher!
At the start of this floor, break the door and battle the squad of Yarideths and Yumideths who are spawning from a fortress past it.
Your main problems in this area are Lava Salamanders. One should walk up to you right away, and then more will slowly come. Watch out after defeating them, as they will explode. This can efficiently end your progress if not evaded.
After these creatures are gone, destroy the Bonedeth fortress and deal with the Kibadeth who come in groups of three, there will be more of them later though. There will also be three boulders past the two flame dragons that can be easily broken. More flame dragons and Kibadeth will attack you, but if you can keep dodging their attacks and reviving friends by summoning, you should be okay.
Three more boulders await, but they are the last ones in the level. Once these are gone, prepare for a tough battle because not only are there more flame dragons and Kibadeth, but there's also a mighty Dragon Boss who will begin breathing fire at you. Get rid of the enemies (the dragon boss drops a golden treasure chest), and keep moving to find a door. This is exactly the same as the last door you saw, so it won't be a problem. Beyond it is a Jeweled Chest and the goal.
If you don't want to restart getting equipment and experience, press start and leave the mission now unless you haven't seen the endings (one of which you'll see if you beat this mission twice or more). If you beat this mission for the first time in the multiplayer demo, you'll unlock Versus Mode.