To beat this rare NPC, you will need a gorilla pet. Gorillas have an ability named “Pummel”. This ability will interupt the casting of the healing spell. It has a 30 seconds cooldown.
This should be the fourth interrupt. As a hunter, you also have Silencing Shot, Scatter Shot and Intimidation.
I have managed to solo this NPC without much effort, just using Pummel when she was casting the healing spell. And maybe a few times I’ve used Silencing Shot.
It was impossible for me when I used a Spirit Beast pet, thought.