Legion Resto Druid artifact quest

Anyone complete the legion Resto druid artifact quest lately? I've been levelling a druid alt mostly as Guardian, but am trying to get the Resto artifact and am hitting a wall. The demon seems unbearable.

The dps NPCs die within seconds. The channeling npc is too far away from the tank to use aoe heals on both, and if I focus on one, the other dies because the demon puts out insane damage.

The worst part is I can't abandon the quest, and I'm worried scaling means it's only going to get harder. I'd be fine just waiting till I hit 120 and smurfing it to get it off the quest log, but it sounds like that doesn't work.