The first void skill Evan had comprehended was the Void Break. Using this skill, he can break the space barrier and open a void rift that he can use to defend against an attack or enter the void space through it.
Although this skill was good and could be used in many ways, he wasn't planning to use it to create his Skill Domain. The reason for this was that it was one of the most basic skills of void energy.
Being able to open a void rift that led to the void space is not particularly special. Even if he hadn't comprehended the Void Break skill in the past, he was sure that once his understanding of void energy reached the 30% mark, he would be able to open the Void Rift solely based on his understanding of void energy.
Using the Void Break skill to create his Skill Domain is definitely not the best option, as his other Void skills are far better than this.
His second void skill, Void Senses, is very simple when compared to his other void skills.