Deep within the Rock Dungeon Gaia is stirring. Living elementals have been spotted raging throughout the dungeon. It is said that even the most battle hardened veterans will need to bring some help along.
Immediately inside there is a strange man who can help you and your party should you choose to venture here. He can craft an Elemental Essence Collector, which is needed to summon the respective Elemental Lords of each element and progress through the dungeon. Once created, the magic will fade from the box in 72 hours, and, if you do not complete the required tasks, you will have to recollect all the essences. Of course, he can't craft something so heavily invested in magic for free. Be prepared for his fee of 10,000 gold.
Once deeper into Rock, you will find several special monsters of the primary elemental types. (Kamori, Karamori, Suimori, Chimori). You will need to capture their Essence in order to perform the ritual summoning to face the respective lord. To do this you must use the Essence Collector by double-clicking it and killing the elementals close to the box.
Several rooms have been transformed by the elemental lords that live there. These are where you will need to summon them once you have collected enough essence.