In addition to providing tools for threat hunters, Endgame also acts as a more traditional endpoint protection program that fills the same role as antivirus, stopping low-level threats automatically. In our testing, Endgame worked in conjunction with antivirus programs already installed on the endpoints, though they do sometimes compete to be the first to stop a threat.
If the antivirus intercepted the threat, it never got to Endgame. Likewise, if Endgame grabbed it first, the antivirus never triggered. None of that really matters in terms of hunting because the caught threat never enters the realm of the hunter. But it does show that Endgame can either fill the role as the primary antivirus protection for endpoints or work alongside whatever program is already being used.