Dark effigy totems

I don't have a dps calculator, but Dark effigy seems fine to me. However, I don't invest any passives into it, and it only has 3 sockets. I generally only use it on bosses and rares. It helps speed those kills up, but as you say most of my damage comes from Essence Drain.

Well I know for a fact that poison counts as 1 stack . Most top effigy builds have envenom on their dark effigy for this reason. But maybe your right about one projectile per different stack type and that's why it's not shooting insane amount of projectiles at 20 stacks of poison