How to get through the Ymir Forest to reach the elves' haven in Tales of Phantasia
How to Reach Ymir Forest
Before you can enter Ymir Forest, you have to go back to Alvanista and talk to Runeglom/Lundgrom, then rest in the inn, then talk to Runeglom/Lundgrom again. Unequip Arche's accessories, then leave the castle. Make sure that you have 15 Remedy Bottles, and buy other supplies and food as needed.
Leave Alvanista, go across the eastern bridge, and go all the way south. Then go slightly west to reach another part of the continent. As soon as you arrive in the new part of the continent, if you have at least 12000 gold, go south and east to find a camp where you can buy a new skill for Cless/Cress. Then go north and west, then continue to go west to find the lake. Go to the south side of the lake to find the entrance. Go north into it to enter Ymir Forest.
You may wish to equip Cless/Cress with Thunderclap. The enemies here are not strong against it, and it has the highest attack of all Cless/Cress's weapons.
About the Forest
Without Arche, this area will be difficult. Mint should have her tactic set to Value HP over TP. If you are having trouble, have Klarth/Claus cast Ifrit. If you fight Lilys/Oak Roots, kill the Lilys, then have Klarth/Claus use Ifrit on the Oak Root as soon as possible. If they surround you, kill the Lilys, then start attacking the Oak Root so Klarth/Claus can cast Ifrit. Usually Ifrit kills the Oak Root. If not, then it will be nearly dead, and Cless/Cress can finish it off.
Don't use Rune Bottles on the ?Weapons that you get from Snake Men. Just sell them. They sell for 75 gold each.
How to Reach the Elves' Haven
From the guard at the entrance, go north and then east across the bridge, then go north and follow the path until it splits. When it splits, go north until you can't go farther north, then go west until you can't go farther west, then go north to the next area.
From the save point, go east and follow the path to the next area. Open the chest to get a Mixed Gummy/Melange Gel, then go back across the bridge and go south to find another chest, which contains a Sage. Then go north and follow the path, and go west to return to the save point.
Go west from the save point and follow the path to the next area. Keep going west and open the chest that blocks your way to get a Lavender. Then, when the path splits, go south to find a chest that contains Lavender, then go back to the crossroads and go west to find another chest that contains Lavender. Finally, go back to the crossroads and go north into town.
Rest in the inn, then buy supplies.
When you approach the north exit of the Elves' Haven, Rambard will join you as a non-playable character. Then you can go north to enter Treant's Forest.