Magic became unreliable. Simple spells, once easy to perform, would sometimes explode at random, killing the caster and those around them. Or sometimes, magic would fail entirely.
Many people , magic users and mundanes alike, reported strange dreams and visions, growing in intensity and frequency.
The normal creatures of the land seemed to grow agitated, attacking without provocation. Scout parties disappeared, failing to report in, those who went looking never finding what happened.
On the night of the full moon, strange wraith-like creatures appeared and began attacking any they encountered.
As questions piled, a group of adventurers were tasked with finding answers, though they seemed to fight amongst each other as much if not more so than the enemy forces seeking to destroy them.
This rag-tag group fought their way into the wilds, following rumor and myth. They encountered many unexpected obstacles, but their adventure eventually brought them to an ancient tower with no doors.
Tested both personally and as a group, it was the only magicless member of their group who found a way inside, at the cost of himself.
With a hole in the wall, the rest of the party entered the tower and eventually found a way to ascend its levels.
One by one they fell to the ancient and unpredictable entities within until a lone survivor remained.
Aided by an ancient and primordial protector, this last adventurer worked up the courage to step into the unknown and through a cunning ploy managed to free his captive counterparts.
Now, with some knowledge as to what was happening, the group attacked and managed to defeat the taskmaster who had taken not only them, but the mother of magic captive.
Once free, they chose to leave the ancient tower, hoping to never have to return,
At the dawn of a new day, with magic seemingly restored, only time will tell if their adventure was a success or if the purge will return.