Once you kill the Demon that killed the Forest Lord, make sure you go back to that same level. The Forest Lord's child "also cub" will now join your party.
Dark Shrine 2
Successfully complete the Cave Of Trials.
Dark World items
Buy all the items from the item shop. The shop will be restocked with items from the Dark World.
Free movement
Go to the battle map view. Switch out any item that is currently equipped with an item that increases your movement. Use your turn to move, then switch your items back to their original positions. You have now moved more than normally possible.
Monsters on your side
If you forgot how to make monsters come to your side(convert), then read the following: First, purify the monster chosen by you to be a part of your team. Second, keep purifying the monster until the box at the top when puryifing says, "Will convert no matter what". Then kill the monster and after you kill it a box will appear saying such and such monster has joined you. If you have already converted one type of monster and want to convert a different monster of the same kind, you will not have to purify it until the point where it says "Will convert no matter what". Make sure you consistently train you monster or it will dislike you and run away.
Switching Characters
When your in battle, if one of your characters can reach the base panal, and your character can't do anything, you can make it walk to the panal and you can switch your characters. It will not heal your characters. You can do this so your characters won't waste their turns doing nothing. Switch wisely. Once they step on the panal, they don't move as far because it is as if they started over from the begining.