Ys Origin/Flooded Prison

Purify the demon statue and continue on. Take the left path and defeat the glowing red monster to unseal the left area. Go left and up to where the switch and chest is. Open the chest to receive the Silver Bracelet. This will unlock the ability to dash by holding either the attack button or skill button while moving. Step on the switch and quickly run to the platform to jump across before it lowers. Go back to the entrance and take the right path. Go up to the switch and use the dash again to jump on the platform to the left before it raises. Continue left and open the chest to get the second tier armor. Go north and up the stairs. Go up the high path and jump across the platforms. If you fall into the water an oxygen gauge will appear. You will need to quickly get out before it is depleted and you drown. When you resurface, the gauge will be full again. Keep going right to the next area. When you reach the floating platform drop and step on the switch to raise the platform. Go back up and jump across. Open the chest to receive an Emerald. Skip the north path for now and go back to the previous area with the two floating platforms over the water. Go north to the next area and defeat the glowing red monster. This will unseal the demon statue. Purify it and continue on.

(Yunica) Boss: Epona
Epona has several attacks with a trident.
 * Quick series of thrusts.
 * Charges and slashes forward with a flame trail.
 * Shoots straight projectiles from the trident.
 * Defends with shield

Epona will temporary stop moving after her flame attack. Most of her attacks can be avoided by jumping to the side.

(Toal) Boss: Hugo
Once the boss is defeated, go up the stairs to the next area to the chest. Open it to receive the Water Dragon's Scales. This will allow you breath underwater much longer. When playing as Yunica or Hugo, you will automatically return to the first floor to talk with the search party. Afterwards, you can talk to Rico to have him strengthen your weapon. Use the Crystal to return to the Flooded Prison. When playing as Toal, there will be a second chest with a Cleria Ore. Go back to the area where you got the Emerald and go north. Use the Water Dragon's Scales in the inventory before going past the waterfall and entering the underwater area. Continue through the underwater path until you surface and go up the stairs. Go around the outside tower and purify the demon statue.

Go back in the tower and defeat the four glowing red monsters to lower the spiked gate. The next several areas will be mostly underwater. You will need to collect oxygen fruit to replenish the oxygen gauge. Monsters may occasionally drop them when defeated and there are also jars that contain them. Skip the spiked turtle monsters because you can't damage them right now and go all the way left. The next area has spikes and water currents that you will need to dash against. On the left side of the third water current through the opening, there is a chest that contains the second tier boots. Equip the boots so you can move quicker in water. At the very bottom to the right is another chest that contains a Roda Fruit. Go the bottom left down the stairs to the next area. At the bottom is a another Ys artifcat, the Levinstrike Warhammer. It will unlock the thunder skill that can now damage the turtle monsters. Go back to where the turtle monsters were and defeat the glowing red ones to unlock the seal to the next area. Before going through, there is a cracked wall to the right that you can use the thunder skill to break. Inside is a chest with the Arthropod Medallion. In the next area, swim up to the top and use the thunder skill again to break the wall. Go through and swim up to the top. On a curved platform is a chest that contains the Celcetan Panacea. Go up the stairs to the next area.

At this point you are out of the water and won't need to worry about any further underwater parts. Go left and jump across on the moving platforms while being careful to not fall on the spikes below. Go up the stairs and at the circular path, go right. At the end is another Roo. Give it the Roda Fruit to receive a Topaz. Go back and take the left path to go outside the tower. Go around and back in and defeat the three glowing red monsters to unseal the demon statue and door. Purify the statue and place the Arthropod Medallion into the door to unlock it.

Boss: Nygtilger
Nygtilger has individual segments that need to be attacked. It will crawl around the central tower before moving to the ground. It has a variety of attacks.
 * Shoot lightning from mouth.
 * Lightning strikes
 * Eject pods that explode a poisonous field after some time
 * Roll up into a loop and spin around the several times leaving a damaging trail

While on the ground, you can climb its back to attack each segment. The pods can be hit to remove them from the area before they explode. When it does the rolling attack, pay attention to when it comes around to identify if it is on the outside, middle, or inner track. Once all segments are destroyed, you can attack the head to finish it off.

Once defeated, the gate in the central tower will open up. Go inside and up the stairs to the next area, the Guilty Fire.