It's been a while since I've done this quest. However, I save all my videos of solo instances. So I took a peek to see how I did it.

I did not fail the instance, so I am not sure if you fail if any of the two support NPCs die. It definitely does if you or Eschiva should fall though. Either way, it is imperative to keep the NPCs up, and I will explain why. This fight is all about optimizing your mana efficiency. You should pop Shroud around 60-70% MP so it will be up again when the battle intensifies. Here are some other tips that might help.

- Gear up. One reason why I did not have trouble with this fight was because I was in a full set of augmented ironworks gear. It makes a big difference because your heals heal for more, your regens tick for more, your DoTs tick for more, you take less damage, you have more HP/MP, the whole nine-yards. If you are not sitting on an abundance of poetics to trade for the gear, purchased/crafted i125 gear is perfectly fine. The upgrade from ironworks doesn't happen until lv56. However, if you have IW, it can very well last you until The Vault.

- Think of the NPCs as DoTs that hold enmity. Don't take hate off of them and let them all tank their respective groups. Cast regen on all the NPCs, and keep those up like you would your DoTs. You can and should assist with DPS, but watch your MP.

- Eschiva has a RIDICULOUS HP pool. Like not even kidding you. Not enough to survive the encounter without heals, but a lot more than the other two NPCs. Use this to your advantage knowing she needs less healing than the other two NPCs.

- Don't forget you have Benediction! Even on NPC's they heal to full, including Eschiva! And take advantage of those Free Cure procs whenever they come up.

- DoT the hell out of everything, eliminate near death targets with Stone 2, and use Holy sparingly.