Lost Dungeons were special.
Unlike normal Dungeons, the magic beasts inside these get stronger.
In the 100-year period of being 'lost' in the Inner Space, a Low Dungeon would improve to Mid Dungeon in around 20 years and take another 80 years to become a High Dungeon.
The difficulty in advancing to each level increases exponentially.
This Lost Dungeon was still transitioning from Low Dungeon to Mid Dungeon.
Once the magic beasts at the Inner Zone reach level 6, it'd be declared a Mid Dungeon.
As Varian headed forward, the aura concentration steadily rose. He thought of maximising his power before fighting the Outer boss.
For instance, he could search for more nests of magic beasts. However, that would take a lot more time. There was no guarantee he would find suitable resources either.
Besides, the Dungeon was still in its early years. That much was evident with the Outer Zone containing only Level 3 Magic Beasts.