Mogall Forest is a rather confusing maze. If you don't follow the exact right path, it will lead you back into the map you were already on from the opposite side. The unobservant player might find themselves walking through the same area several times in a row before realizing it. It's advisable to hotkey Force in here to or .
As soon as you enter, you'll see a green Ape monster jump into a hollow stump. You can use Force on it to scare the monster out, and following the advice you received, the monster will run down a path. Follow it; this path is the only one that won't cause you to get stuck in a loop. If you lose it, the first one goes down through two maps. In this map, there are a few stumps. When you hit the wrong one, an Ape will jump out, angered, and attack. Defeat these if it should occur. In here are also many of the rolling logs on land, similar to those in Kolima Forest. Push the vertical log right, then push the horizontal one south. Walk along the newly opened path to get on the right side of the vertical log and push it all the way to the left again. Before going on, grab the Nut in the tree near this point with Catch. Now, approach the horizontal log from the south and roll it to the north, into the water. Jump across and hit the stump on this side of the water with Force. The ape will jump out and run down the right path. Walk two maps more into another area with 4 paths leading out of each side. Hit the right stump with Force to follow an ape down the right path where you find a chest that has an Apple which boosts attack. Go back through the only path to the original area. Hit the left stump with Force to scare the Ape down the southern path. Follow it for two maps into another wide area.
Here, walk to the right side near a rolling horizontal log; its movement is blocked by a rock. Use Move on the rock to push it backwards. Now you can roll the log away and go through the newly opened route. down here are two logs, one horizontal (blocking your progress) and one vertical. Roll the horizontal one south, then go behind the vertical one and roll it to the left. Go south and turn to the left to see a Venus Djinni. Fight it and defeat it to gain Quartz. If it succeeds in running away, leave through the same path you entered and try again. Once you've obtained it, roll the horizontal log all the way north and then move the Vertical one left into the water. Jump across and use Force to move the ape into the stump on the left side of the map. Walk all the way back up to where you entered from, then go down the bridge. Walk to the left and hit this stump with Force to make the ape scurry down the left path. Two maps to the left and you'll wind up at a 4 way split with three stumps in it. Hit the left stump to send an ape to the left, leading to an area with a chest. Push the rock up, then right twice with "Move" as you roll the log to the right. In the chest you'll get an Elven Shirt, which boosts Agility by a fair amount. Return to the previous screen with 3 stumps and hit the center one to send the ape running again to the south. This time, it's just one map.
Move to the left down a bridge until you see another vertical log blocked by a stone. Use the same tactic as before, Move the stone out of the log's way. Jump across and Force the ape into the southern stump. Jump back and go south along the leftmost path until you reach the logs. Push the vertical log one to the right, then push the horizontal one south. Walk left, then down the path until you come to a different vertical log; roll it into the water and jump across to get to the southern stump. Force the ape down the southern path. Go one map down after it, then save. Ignore the stump here and keep moving south. As you attempt to pass, you'll be attacked.
Boss Battle: Killer Ape
This is a giant blue ape, presumably the one you've been following through the forest all this time. Use your Djinn as much as possible; Zephyr increases agility (attack speed), so it makes a good first round choice. The Killer Ape possesses the skill Bind, which can seal you from using Psynergy, so if this happens be ready with some attack Djinn to make up for it, or healing items to cure it. Quartz, which you picked up here, has the ability to revive a downed party member, so be sure to keep it (and its owner) ready at all times. By the second or third round, you should be ready to hit it with many powerful summons. Not only will the summons deal a lot of damage, but they will also increase the power of same element attacks used after them, so it'll keep your rate of damage up while the Djinn recover.
The fight isn't too hard, and once it's defeated just take a few steps to leave the forest.