After reaching Flame Star from the Star Station, follow the boss coordinates on the mini-map to find Dragon Island. In the center of Dragon Island, touch the Flame Break Sword, and the Ancient Black Dragon will appear, initiating the battle.

Upon defeating the Ancient Black Dragon, you can collect the Flama Break Sword, and a Lava Stone and a Treasure Chest will appear in the center of Dragon Island.

Ancient Black Dragon

After crafting the Lava Horn, return to Dragon Island and use the horn to activate the Lava Stone, summoning the Black Dragon of Lava.

After defeating it, the Lava Stone's position will be replaced by a Chaos Stone and a new Treasure Chest.

Black Dragon of Lava

Craft the Chaos Horn and use it on the Chaos Stone to summon the Black Dragon of Chaos.

Upon defeating it, the Chaos Stone will refresh, allowing you to summon and fight repeatedly. Each time you defeat it, a Treasure Chest will be generated.

Black Dragon of Chaos