Holyshock synergy is for the lightning dmg componet for FOH. Unless you are going for gears like griffon, -5/+5 lightning jewels in gear and griffon then you max out holyshock synergy for FOH. If you are just only needing the holy dmg component of FOH then you can just put 1 point into holy shock. The rest of the point you can use for other purpose.
Depend on what you making. A pure FOHdin, a hybrid FOHdin?
Check out my hybrid build here: