Are Buffs considered Spells - Blackflame Question

Im currently testing a "passive" Lich build where im using resonating shield with blasphemy curse stacking.

And im wondering if buffs like Herald of Ash and Magma Barrier are considered spells?
Reason is that I think i need those maybe for my build and since im going all in on Chaos I will have to use Blackflame node or the ring that converts fire damage to chaos.

So does anyone know if Blackflame node that converts fire damage from spells to chaos, works with Blackflame?