Phaeton's father, the sun-god, promised to grant Phaeton whatever he wished. Phaeton declared that he wanted to drive the sun-chariot, and although the sun-god tried to discourage him, Phaeton refused to choose something else, and the god was not able to retract his promise. The horses that drew the chariot, under a weaker hand, burst out of control, and Zeus was forced to slay Phaeton with a lightning bolt to save the world from burning up. Phaeton brought about his own downfall by his impetuosity and pride.
means to cause a downfall
because it is a myster
He died prematurely.
Downfall in what? A bigger or more organised gang beat them. Which is not too difficult. Weeds do it.
Grieving their brother's dead they turned into poplars.
His death. He was emperor until he died.
because they want something change to their government
The horses failed.
Yes, the compound noun 'downfall' is a common noun, a general word for a loss of power, prosperity, or status; a general word for the cause of such a loss; a general word for any downfall of any kind.
they died cause they shot each other
Nationalism, corruption, technological and economical downfall
The main cause was the conquest by the Ottoman Turks in 1453.