I don’t see it as an emergency heal. The set up alone it too time consuming. That’s where regrowth will shine, for all the reason listed above. Plus we have NS and SM as well.
For predictable incoming damage however, I see it being quite valuable. I generally keep hots rollin on the tank regardless of what’s going on, so ramp up time on tank heals would be minimal.
For dps, the predictable boss damage like Spit Gold in kings rest, for example. On tyrannical weeks at higher keys, it will absolutely chunk your health. Pair that with weekly warriors who don’t utilized their cool downs properly while they dance in the puddle it leaves and youre in for a bad time. Regrowth spam has gotten me through this before, as I’m able to predict and react to the damage, even if the player isn’t, but it’s often barely enough and I’m making it by the skin of my teeth.
As few months back, this same scenario was being discussed about spamming regrowth to deal with this ability. So I checked higher logs to see how people in 20+ deal with it, and sure enough they are spamming regrowth too.
If the numbers from my beta testing prove accurate, nourish becomes a spamable swiftmend equivalent heal. Such a powerful heal would nullify this ability with ease, in less time, with less mana, and less urgency.