If anyone studied dungeons, a question would naturally arise.
If low dungeons can hold only up to level 3 magic beasts, then what happens when a beast reaches level 4?
It enters a mid dungeon.
How?
The dungeons' spaces were interconnected. That was also the reason Cross Tunnel Formations work between dungeons as well.
The process of a magic beast exceeding its dungeon's level limit was called Ascension.
Once it happens, the dungeon's space would then open up a connection with a higher dungeon and send off the beast.
But the real problem only started.
During this short period when the space was open, magic beasts from the higher dungeon would descend into this dungeon.
And because of that, the total power of a dungeon would skyrocket, and naturally, a Dungeon Break would occur.
However, it wouldn't be magic beasts of that lower dungeon that would break outside but the magic beasts of the higher dungeon.