Accum! Accum! Accum!

The reason Vara Accum was so powerful was for an extremely simple, but broken reason. It was a material-based Nature but behaved like an energy-based Nature.

It became stronger when stacked!

Energy-based Natures became stronger as a cultivator progressed through the Life Stage. Material-based Natures had a material density limit, beyond which they would lose their structural integrity and experience some sort of chemical reaction.

This chemical reaction would transform the material, causing the cultivator's Human Avatar to implode on its own. It was why many incomplete cultivation techniques resulted in Free Humans being unable to progress beyond a certain level in the Life Stage.