Maybe they(The Fury-ies) have Poison Immune, check their Affixes on their name next time…
So the Effective mythic affix doesn’t work on elements immune monster?
Effective makes your damage be the type they’re weak to, as defined by the type of enemy they are. Those are fire elementals, so they’re weak to ice. If they have ice immunity, they’re now immune to your damage. Get yourself a red Ignore Resists affix to bypass immunes and resists
Ok. Got it! thanks!