Going Through Forbidden Otherworlds

From the back of the book: The eternal empire of Velzeal consisted of thirteen cities sheltered from their world’s twin suns by the tall shadows of the surrounding Titanfang mountains. This civilization of a reptilian race was ruled by emperor N’taka the wise. The gentle Kingdom of the moon of Nibu was in the 15th year of peace with the neighboring tribes of ice barbarians, its aerial hawk-knights flew only as messengers. Within a month of each other both polities had been sacked by an army of Portuguese conquistadors. How they did that is the even more terrifying secret contained within…