Scaling the 
Poisonous Concoction levels with your quiver, you want multiples of 50 when scaling gem levels off your quiver. Example 350 400 450 etc.
You getting this done with 
Widowhail and using jewels sockets from the tree.
Jewels stat priority: - % increased bonuses gained from equipped quiver till you reach the next break point.
You need +50 spirit you can get this from your body armour and amulet combined. Or just from your body armour.
Amulet annointment is 
Ancient Aegis
Helm: just get huge Energy shield and resistance
Quiver: Must have +2 projectile skills, crit chance (can get it as an implicit but this is expensive)
EDIT: Since 0.1.1 patch the bow damage not applies to the Poisonous Concoction
Others: Attributes for your gear gems, resistance
Mapping setup:
When you just doing maps you need to switch out 
Maligaro's Virtuosity to a rare gloves and your rare boots to 
Corpsewade
Ranger
Pathfinder
Chaos Inoculation as defensive layer and we stacking energy shield and evasion. Even with that much invesment we reaching more than 5k energy shield and while mapping this will get doubled because of the 
Grim Feast.
Wind Dancer. The damage side is coming from the Pathfinder ascendancy and 
Overwhelming Toxicity. In PoE 2 the poison scales from the maximum hit damage as well. So we will stack critical chance and crit damage with 
