One of the best spectres of Necropolis league, T17 viable. They are very tanky and use poisonous concoction which has projectile overlap with greater volley and will always poison on hit. In this video im using chaos crit version, but full poison variant could also be viable. Also another option is to mix in 2 or 3 Necrotic Bones spectres to help with clearing as they scale off same support gems.

My PoB https://pobb.in/_YWtnaMCUPom

My char is quite squishy, by all means edit my PoB and make it tankier to suit your needs, this is just a rough template.

https://poedb.tw/us/Tawhoa_Shaman#TawhoaShamanAncestralDruidStandalone

Get them in maps with the Allflame Ember of Tawhoa.