What champion points affect poison builds?

Jaiden

Building a bow poison build using poison injection, acid spray, lethal with 5 piece morag and 5 piece hawk's eye. I know thaurmaturge increases poison already, but what secondary champ points? does poison work off spell or physical being it's a weapon skill that uses stamina and seems to be affected by +weapon damage modifiers ? Should i got elfborn and spell erosion? or should i go the physical route with piercing and precise strikes?