The Twisted Wand Castle collapsed.
The Sage of Balance, Seneka Windell, was defeated by a boy wielding a Wand -that is, the greatest, most powerful category of staves a mage could use- made by himself and his friends. The Wand of Hope.
The Sage that lost faith in those she swore to protect broke the seals of the sages, making the monster realm connect with the world in more places and increasing the power of its inhabitants. She wanted to wipe out everything and remake the world, but the monsters still needed the presence of the populance she so despised... she bode her time until she could collect all of the magic in the world.
She had all seven of the original Sage Wands, which held the remnants of the Creator's power: Fire, Water, Earth, Wind, Light, Dark... and hers, Balance.
Using all of her hate, rage, and sorrow, she ordered the monsters to gather.
The son of the Sage of Light, having been recognized as a fellow Sage by his elders, having found one of the trees from which the original Wands were carved, wielding all six of the Lost Magics, with knowledge of powerful combinations of Runes, with support from his friends, and in command of mighty monsters himself, did battle to stop her.
At the end, the magic left the world, and so did the monsters.
Even her fury, her madness, left her mind.
But nothing ever truly fades.