PRINCE: One who destroys and destroys with Classpect
VOID: Secrets, Lies, the Unknown, Absence, Shadows, Ignorance, Lack of the Five Senses
A Prince of Void acts in a fashion similar to a Light player (as tends to happen with destroyer classes, having similarities to their opposite Aspects), using the Truth as a weapon. They can destroy the obscurity surrounding something one would rather keep hidden, drawing everyone's eye to it.
A Player's secret infidelity, their treachery against the team, it all can be found and brought forth at the Prince's discretion. As the Prince of Void, the Player will be able to destroy the obfuscation around a person's words or actions, knowing their true intentions.
The Prince of Void would be able to destroy the Void in a literal sense (Shadows), being able to disperse fog and other obscuring factors (which could also be things that block vision like walls/ceilings/etc. They might even have X-Ray vision) and be able to break through the wall of darkness until the Light can seep through, allowing them to see.
As for absence, this falls in line to what Roxy could do as a Rogue of Void. If the Prince of Void had need of a legendary weapon, all they would have to do is destroy the weapon's very non-existence to bring it into being. Paradoxical, but logical!
As for Ignorance, this ties in to the Truth. The Prince of Void destroys Ignorance by utelizing the Truth obscured in the Void that they discovered, bringing to their team's attention certain secrets: such as how the Black Queen keeps her Ring hidden within the Royal Vault instead of on her person.
The Five Senses is...interesting. As the key ways in which we process information, the Prince of Void would be able to completely ruin them. The Prince of Void could blind, deafen, numb, and ruin the scent and taste of the enemy, driving them mad as they are blanketed in pure Void, pure lack of feeling or sensory. Alternatively they could destroy the lack of these senses, destroying the Void around these things, being able to restore the Senses but only to what they once were (removing the debuff but not being able to buff them) (that would be Sylph territory).