The first fiend

Take that floor

With the way open all you have to do is go down the other two floors of the Earth cave and revive the crystal at the shrine of the Earth Crystal. Sound's easy right? Well the first part of it is easy enough, as the monsters on levels four and five of the Earth cave aren't significantly stronger than those on the first three levels of the cave.

Lich in all it's terrible glory

At the bottom of the cave there is a small shrine and an orb in front of it. Talk to the orb and you will find that it is the fiend of Earth also known as the Lich. Of course you go into battle once you talk with it. The Lich is a much stronger boss than anything you have fought before. Even with my warrior and black belt hasted I wasn't able to do all that much damage to the fiend. I found the firaga and diara spells worked quite nicely against it though. The lich can deliver a lot of pain to the players as it has spells that attack the entire party as well as melee attack which can paralyze you just those of some other undead monsters. In the NES version of the game I remember the lich having 400 hp but in the android version of the game it has significantly more hp.

The first crystal is saved

After overcoming the lich I was able to revive the Earth crystal and complete the first fourth of my quest as the light warriors. There is even a teleportation device behind the shrine that transports you to the entrance of the Earth cave. So now you can return to Melmond with your head held high as you actually did light warrior stuff this time.