During the Flavors of Mayhem quest, Rose requires the player character to shoot the syringer at an enemy, with the intention that the player character hide during the 60 seconds that the enemy is temporary buffed, and then easily killing the enemy while it is weakened during the subsequent 60 second period. This weapon will not work on robots; use it only enemies that are "flesh and blood."
However, this weapon is equally effective with other teammates to give them a temporary buff for 1 minute, with the understanding that during the subsequent minute they will temporarily become more vulnerable to enemy attacks.
Karma syringe details
Buff (30 seconds)
+15% damage, +50 max HP, +25 DR, ER and RR
Does not work on Essential NPCs, SBQ, Wendigo Colossus or any Robot/Turret
Debuff (60 seconds after buff expires)
-50% unarmed damage, -100 DR, ER and RR
100 magnitude stagger (1-2 seconds)
Only works on Players, Robots/Turrets or Yao Gaui.