It is a white visor when used by the Tech Team, and it is gray when used by Death. It blasts a green laser up in the sky, with the beam being more focused on Death's visor as opposed to the Tech Team's being depicted as more wide-spread.
When it is used, the green laser appears, which boosts the user's health. Despite healing the user's health very quickly, the user is completely vulnerable to attacks while the visor is activated, as they cannot move or dodge.
The only way way to prevent usage of the visor by your foes—in this case, Death or the Tech Team—is to keep punching or hitting them constantly, preventing them from using it and simultaneously draining their health. This is also covered in the Strategy list.