Destiny 2 - Mykel's Reverence Harmonic Resonance x2 Damage Increase (Root of Nightmares Sidearm)

Appears to be approx 3% damage increase for 1 stack and 10% damage increase for 2 stacks. I've also noticed that this works against any hive enemy in Savathun's Throne world, so this is not limited to just Hive Guardians.
I have footage of the same test conducted with the shotgun and GL on my channel, increase in damage values are the same for primary, special and heavy, and across all different enemy ranks.

[@dann1483]

Is the shotgun worth crafting

[@SpaghettiTop]

Y U S

[@deividplays]

Do you know if Nezarec counts as a Tormentor for this?

[@Mikediszel]

That's a pitiful buff I'll pass

[@oddball6064]

Bear in mind that this stacks on top of any damage perk you have on the weapon. Your frenzy goes from 15% to 25%