Rock River, not a river of rocks, but a river of magma.
For some unknown reason, the magma here flows out from underground, forming a nearly hundred-mile-wide, tens of thousands-mile-long river of magma.
Within the river reside many fire-type Secret Spirits, among which there are extremely terrifying entities, such as the very famous Lava Dragon King, a gigantic creature with a destructive power even more horrifying than an ultra giant.
In the Grotto Heaven, hardly any Secret Spirit dares to challenge the Lava Dragon King in the Lava River, as the king uses the river's geographical advantage and its endless firepower, making it one of the strongest Secret Spirits in the Grotto Heaven.
However, if it leaves the Lava River, the Lava Dragon King's combat power loses its overpowering edge.
Within the Lava River, the Lava Dragon King breeds massively, with its powerful offspring increasing in numbers, further deterring anyone from challenging them due to the geological advantage.
