Enemy Revealed

Post-Pilgrimage, Day: 166.
The Corrupted walk among us.
It started with the Warmongers. But their rise & fall was but a mere symptom.
Someone or something sinister is turning the hearts of Astra Novans towards darkness, one soul at a time.
Meanwhile, the newly unified Settlement Army has succeeded at keeping the natural fauna at bay.
But recently several Explorer parties have gone missing.
A lone survivor is found, mortally wounded with a dying message:
“The horde is coming.”
Could these threats be linked to the end of the Five Worlds?
How can they be defeated?