
The first stage, called Devoid Diu, can be considered a shadow of what the Devoid truly look like. This rough sketch/design piece illustrates the hollow nature of their appearance.
As a Devoid grows in strength, experience, and energy consumption, it can develop into the next stage. Each stage allows for a Devoid to slowly regain that which it doesn't normally physically have while existing in the human world. In other words, a Devoid at a higher stage will become more powerful and appear more complete.

Which of these two seem scarier? Diu, with its long bony arms and reptilian jaws instead of an abdomen? Alio, with its stretched flesh and limbs, appearing to be scheming? Or perhaps both are disturbing in their own ways?