Severus Snape is an extremely powerful Genjutsu user.
One genjutsu he has is called Legillimency. It allows him to go into the minds of his opponents and extract memories. First of all it distracts and sometimes incapacitates his opponents in combat. It also gives him access to information, allowing him to learn valuable intel.
He also has a genjutsu skill called occlumency. This is a very difficult technique where he breaks a Genjutsu. Snape can even do this without his opponent realizing that the genjutsu has been broken, giving him a significant advantage.
One genjutsu he has is called Legillimency. It allows him to go into the minds of his opponents and extract memories. First of all it distracts and sometimes incapacitates his opponents in combat. It also gives him access to information, allowing him to learn valuable intel.
He also has a genjutsu skill called occlumency. This is a very difficult technique where he breaks a Genjutsu. Snape can even do this without his opponent realizing that the genjutsu has been broken, giving him a significant advantage.