Reverse Arrays.
If I am going to explain this, then it would be better if I give a brief of Arrays first.
You probably already know that arrays are a combination of signs and symbols drawn on a paper. When mana flows through them, they activate and do their function before getting erased on their own.
The erasure is by destruction of the material or the surface on which they are built on.
Arrays, in essence, can be classified into two types again. Open Array and closed one.
Simply said, closed Arrays function like a mana circle that takes in mana and does it function.
As for open arrays, they take in mana as well, but they also pass out mana from certain open ends. Think of an open arc in a mana circle that doesn't connect with anything.
With that much basic knowledge in mind, we come back to Reverse Arrays.
Reverse Arrays are a type of open array that takes in mana from the open ends and keeps storing inside the circle.