Every victory at the top of Olympus will reward you with fragments of the boss of the moment.
Once you've collected all the fragments of a boss, he'll join your breeding farm.
You can get each boss only once.
After you've won the divine boss, you'll earn fragments of the special horses of the moment every time you win until the boss changes.
The divine boss of the Ascent of Olympus mode changes periodically.
You can win fragments of special horses by progressing through an Ascent of Olympus game.
You can win them at end-of-threshold challenges and at certain events.
These fragments are drawn from a selection of 5 special horses that will change periodically.