So I've read the tooltip and I feel like even though I use it, I'm not sure if I'm using it correctly or understand precisely which spells apply to it. It just just triggered (from healing) by HT, Regrowth, Swiftmend, etc. in so far as the single target heals cause damage to nearby targets? Or does it cause damage AND healing to nearby allies/targets?
And for damage, I'm assuming trigger by Moonfire (initial application) and Wrath? And that therein causes healing to nearby targets?
I just feel like when I use it, the effects are underwhelming which leads me to think maybe I am not using it right?
I would have just read the Resto sticky but it isn't updated for 6.0 and wasn't sure if any of that still applies at 100.
When NV is active, your heals will cause extra healing and damage to a nearby target, and your damage spells will only cause extra healing. Anything single-target will trigger the effect, once per application. This means a "proc" with every heal you cast, every tick of a single-target HoT, and the same for nukes/DoTs. It's not that powerful for balance, but it's very good for resto.
There's no internal cooldown or anything. For resto, it essentially grants +30% to all single-target healing for the duration, and it has a 33% uptime. The caveat is that you have no control over who receives the extra healing, though it can proc on the target of the healing spell itself, and it shouldn't hit people at full health if there's an injured target in range.
When raiding SoO, NV often made up around 7-8% of my total healing, which is more than Swiftmend and Lifebloom. It's great at recovering from widespread raid damage, and the cooldown is short enough to use several times per fight. As an added bonus, it does like 1-2k DPS throughout the fight as resto, though keep in mind that the damage will break CC effects (but will not hit neutral mobs).