While the Pain Gun deals miniscule amounts of damage (before patch 1.39, the pain gun dealt no damage), targets painted by it's beam suffer from reduced movement speed as well as taking increased damage from other sources. Very useful in PvP environments where Agents can have high Protection and/or move speeds, as well as for picking out individual targets. In PvE, the Pain Gun can be used while the team doesn't need immediate healing (perhaps due to a Force Wall or Dome Morale Boost) and a significant threat is present.