Danger Level: 20
Location: South Clearbrook Traverse, up on a hill north of the bridge leading to the Southern Sunshade Sands
One of the earlier optional dungeons, the Twin Falls are a great place to level up your party in preparation for any of the Chapter 2s available to your team. You'll likely be ready to tackle the Twin Falls after gathering all of your party members, though with the right strategy you can go through here earlier than level 20.
You'll run into the following enemies in the Twin Falls:
- River Froggen IV - Weak to Staff, Ice, and Dark. Can use Inspiration to buff its entire party's attack power and Soporific Slash to put a target to sleep.
- River Froggen V - Weak to Staff, Ice, and Dark. Has a Raging Fists attack that can hit several random targets for a significant amount of damage.
- Blood Viper - Weak to Dagger, Ice, and Dark. Likes to use Wildfire to hit the whole party, though it shouldn't cause much damage.
- River Fly - Weak to Polearm, Bow, Ice, and Wind.
- Warrior Wasp - Weak to Sword, Polearm, and Axe. Their Mandible Crush attack can do a fair amount of damage to one target, and Numbing Needle is always annoying since it can paralyze one character.
- Shadow Bat - Weak to Sword, Polearm, Bow, and Ice.
- Salamander - Weak to Dagger, Ice, and Light. A powerful melee foe that can one shot weaker characters. Keep it stunned until you wipe out the rest of its entourage.
Immediately after entering Twin Falls you'll come to a save point, and the path branches in three directions. We'll start by going east. Run all the way to the far side of the cavern and you'll find a northbound path leading to a purple chest that contains a Psychic Staff. Return to the main path and head north. Take a left when you get the chance and the path will curve inward. You'll find a chest containing an Energizing Pomegranate (M) on your right, and if you keep following the path south you'll wind up back at the entrance.
Next up is west. Follow the path west and then north until you see a chest ahead containing a Healing Grape (M). Go northeast from here until you start to see light at the end of the cavern and a nearby torch. Look southeast of the torch to find a split path. On the left along this path is an Inspiriting Plum (M). Go any further than this and you'll wind up back in the east of the cave.
As you approach the torch you'll get a message warning you that the sense of danger is overwhelming. Say you're ready to proceed and you'll be pitted against the boss of this area, the Monarch.
Monarch
Weakness: Polearm, Bow, Dark
What a nuisance. Aside from its powerful normal attacks, the Monarch specializes in Skills that target your whole party. Galestorm hits everyone for Wind damage, while Mass Slumberwave can potentially put everyone to sleep. When the Monarch is past half of its health it can also use Numbing Dust, which can - and often will - inflict unconsciousness on everyone. It's not fast enough to take full advantage of the party being debilitated, but will still put the hurt on if everybody is conked out at the same time.
This fight isn't that difficult so long as you bring along characters who can target the Monarch's weaknesses. H'aanit and Olberic in particular are great here, as they can use their multi-hitting bow and spear Skills to demolish the Monarch's defenses and leave it vulnerable to other attacks. Alfyn is quite useful in this fight, as Concoct can quickly dispel both sleep via Rousing Mist (Soothing Dust and Sleep Weed) and unconsciousness via Lucid Mist (Soothing Dust and Addlewort).
Once the Monarch is out of your way you can finish up exploring Twin Falls. Further north you'll find a purple chest containing a Refreshing Jam, and if you check along the path to the right of the chest you'll find a hidden walkway that leads through the scenery to a second purple chest that you probably saw earlier but couldn't reach. It contains 5,000 leaves.
With Monarch dead and your treasures collected you'll be done with Twin Falls. Be warned, however - there is a very small chance now that Monarch is dead that you can run into two of them as a random battle. You may want to teleport out to a town rather than walk out on foot if you had trouble with the boss, just to be certain you avoid this possibility.