-% Enemy Poison Resistance decreases enemy Poison Resist and Poison Length Reduced by %, but only if < 100%.  It only applies when poisoned by the user.
- When present on two weapons, the percentages of both are summed and applied to the enemy.  
- It does not apply to poison damage applied by pets summoned by the user, so it does not apply to Blade Sentinel, Poison Creeper or Necromages. 
- It is only applied whenever a new source of poison damage is applied, so removing it afterwards will have no effect on remaining damage rate or length; adding it after a target is poisoned will have no effect either. 
- Monsters normally have no PLR so -% EPR increases poison length by the displayed amount, to the floor of -100% (increasing it by 100%). The only possible exceptions are the Ancients, whose items can spawn with PLR suffixes: Korlic and Talic can spawn with PLR > 99%, which always reduces poison length to a single frame.