Item-cast aura as a synergy

I know that item-cast auras from Insight and Cure synergize with

Prayer, which is a common merc setup

But what about

Resist Fire and

Holy Fire? People like to run Flickering Flame on dragondin and self-cast

Holy Fire builds, but I'm not aware of a damage synergy between the auras in this situation

Presumably this doesn't this work? I searched, I but haven't been able to find an answer or detailed game mechanic explanation

Unless you're talking about summon druids as the one exception to the rule (well, and shadows, kind of), synergies only grant a bonus via the hard points you have invested. Points from gear (regardless of that being aura lvls or direct +skill) do not add anything.

The

Prayer example works because the merc actually has

Prayer as a hard skill, resulting in said

Prayer granting a synergy bonus to the item-based

Meditation and

Cleansing.

The

Holy Fire example however wouldn't work because flickering would only grant item-based points in

Resist Fire which doesn't add any synergy bonus. Hard points in

Resist Fire will give a pally a synergy bonus to item-based

Holy Fire auras but again that's only for the hard points you actually have invested in

Resist Fire. The reason some folks run flickering on HFdins regardless is the -res on it and the aura countering the res lost due to the fire sunder.