City of Light - M. Marinan - Bog

It's the end of the world as they know it.
Jon's had a hard week. Sure, he's just defeated the seemingly unkillable White Prince, becoming the first human to ever destroy a Creature, and fulfilling a remarkable destiny he never even imagined. And sure, he's made friends with his uniquely gifted neighbour Tarie, and has reconciled with pretty, time-travelling Bets.

But his carrier father keeps tossing him into awful situations, an old school friend keeps trying to kill them all, and his birth mother's just shown up at the door, unaware that she's jumped through time and has been missing for seventeen years rather than a single afternoon.

Worse still, the whole world's been taken over by a new power that will destroy anyone it can't control. And it's got a plan that goes well beyond statues and pledge marks.

But the immortal Amaranthus also has his own plans which involve Jon, Tarie and Bets - if they can live long enough to achieve them...
This is the seventh and final book in the Across Time & Space series:
The Eternity Stone
Mountain of Glass
Desert of Fire
Desert of Ice
The Hidden Door
Whiter than Snow
City of Light