Is a power attack damage roll also a melee damage roll? The first line of the power attack damage roll section says “Though power attacks are melee attacks, they do not resolve damage the same way.” The following lines go on to talk about how to determine the POW of a power attack comparing the base sizes of the models involved, but it is unclear whether or not the power attack damage roll is still also a melee attack damage roll. I would like clarification on this, because I am not sure if the models being hit would get bonuses like unyielding, which would make sense to me conceptually, and it also makes sense that a model making a power attack would get bonuses from things that increase their melee damage, like Puissance.
It is a Melee Attack but not a basic attack.
That’s not really relevant to the question. If a power attack damage roll is not a melee damage roll, certain abilities and effects do or do not apply to it. Whether or not it is a basic attack isn’t a factor.
Yes. A power attack damage roll is a melee damage roll. Power attacks are melee attacks. The following paragraph is pretty crystal clear on how power attack damage rolls differ from regular melee attack damage rolls.
The italicized bit is how they differ. Nothing else in the rule changes how modifiers to the damage roll affect the damage roll, so things like Puissance – which specifically gives “+2 to its melee damage rolls” – apply.