Dark Effigy Doesn't respond to multiple stacks of poison

Unsure if this is a bug or not, Dark Effigy will attack enemies that are poisoned, but will not fire extra projectiles at targets afflicted with multiple poisons. If this is intended perhaps the text was meant to specify "unique debuffs".

Also encountered this, if it not working with multiple poison stacks is intended behavior then it would be best to mention that in the skill tooltip.