A shimmering energy ripples out from the point you chose within range. The area of the zone consists of up to ten 10ft cubes, which you arrange as you like. Each of the cubes must be contiguous with at least one other cube. You may chose to make yourself immune to the effects of this spell when you cast it. 

Creatures within the zone immediately lose all of their personal memories, though they retain their name, skills, and basic knowledge of the world (though they may not have the full context for this knowledge). A creature can attempt to resist this effect with a charisma saving throw. On a success the creature does not lose its memories and takes 5D10 psychic damage. They must repeat this save at the end of each of their turns. 

Any knowledge gained or memories made while in the zone are lost upon exiting it and the creature's personal memories are fully restored. If a creature re-enters the zone, they regain the memories and experiences from the last time they were in the zone (losing their "outside" personal memories again).

If the caster maintains concentration on this spell for the full duration, the zone becomes permanent, unless removed by a wish spell. The caster can only ever have one Zone of Severing active at a time. If a new zone is created, creatures entering it who have been affected by the spell before, retain all of the memories made in the previous zone.