I always hear thunder coming from the cave to the east. It's so scray, kupo!
The Cave of Fulmination (雷鳴の洞窟, Raimei no Dōkutsu?, lit. Cave of Thunder) is a cavern in Final Fantasy Dimensions. This optional dungeon, located to the southeast of Dragon Roost, is where the player can obtain the Eidolon Ramuh.
Arriving at the fourth floor of the cave, the party notices an old man with long white hair. Sol tells him that the cave is not a safe place for someone his age but Aigis tells Sol to be careful, as the old man does not seem like an ordinary elder. The man, who until then had his back turned to the party, turns around to face them and laughs, calling them "feisty young cubs". He pushes back the party with a lightning attack and Dusk realizes that can only mean he is the legendary Eidolon Ramuh, Lord of Thunder. Ramuh recognizes the party as the Warriors of Light and, while the Crystal has deemed their spirits worthy, Ramuh is not yet convinced. He initiates a battle with the party but is ultimately defeated. Impressed by their strength, Ramuh mentions that they might just be strong enough to save the world. The party then obtains Ramuh as an Eidolon.