Chieftain: Ramako sun's light and rigtheous fire interraction?

"Cannot be ignited" + righteous fire, how does this nod will work with righteous fire?

does this mean you will take zero dmg from righeous fire while burning your ennemies?

Nope, because Burning (fire damage degeneration) is not Ignite (elemental status ailments that causes burning damage).

The former is caused by many sources (Ignite, burnign ground, righteous fire)

The latter is caused by fire damage hit + crit or fire damage hit + chance to ignite

Rise of the Phoenix has the same modifier for low life state, and the modifier has nothing to do with Righteous Fire, which is not an ignite.

ok thx