Shadow of the First Sin
Wounds in the Flesh of Reality
The misfired warding spell did more than catapult the survivors into a strange world- it also left fragments of other worlds intermingled within the fabric of this one. The boundary between these Shards and the material plane are abrupt, sudden, but also permeable- there is nothing that keeps one from entering the material space of a Shard, save for local conditions. A famous example of this phenomena is the Skyward Fall of Ginyn; here, a Shard whose gravity is the reverse of our own lays upon the river, causing the water to abruptly shoot into the sky for more than 100 paces, whereupon which it reaches the edge of the Shard and the native gravity takes over once more, leaving the water to shower down over the surroundings.