So I use exactly the set up you're describing , I've heard some ppl say holy fire ticks stop nova ticks but can't honestly say I've noticed that to any degree. Meanwhile the fire golem aggro + thorns means I can actually kill bosses and dclones
It's great
Yes, poison dmg is applied every frame, but it skips any frame where any other form of dmg is also applied.
The only exception to this is open wounds.
Luckily, the holy fire aura from your 1 hard point fire golem has a small radius, and ticks only once per 50 frames.
You’ll be avoiding most of it be just flying around and applying your psn nova to as many mobs as possible, leaving them dying in your trail outside the small pulse dmg.