The Builds:
[build=A_Me Vale;OwVTE4B+ViHRnpzzGcJABcFwEAA]
[build=E_Mo Pyro Tank Vale;OgNDoMz/Qfe1C0C3MlV8C0l0DA]
As you can see, the Sin build is very similar to a typical chamber build.
For the Ele build, Energy Storage is key, so use a headpiece with +1 to Energy Storage and a rune of Superior Energy Storage. Also use a rune of Superior Fire Magic. In addition, use Survivor Insignias and runes of Superior Vigor/Vitae to offset the health loss from the Superior Energy/Fire runes. Lastly, use a caster weapon, and a fire offhand with preferably a 'forget me not' inscription and a +45hp while enchanted mod.
The Strategy:
With the A/N & N/Rt Vale teams - both the Assassin and Necro clear the reaper monument. However, with a bad pull the Graspings can rush the Necro and quickly kill him.
With our new approach, the A/Me can clear the reaper solo - very similar to how chamber sins can solo-clear the first part of the chamber 'on the stairs'. Basically, just ball everything up and use your hex spells to kill them (of course don't stand to close to the Coldfires - or they will get you with Frozen Burst).
Once the reaper is popped, either the A/Me and E/Mo may do the Wrathful Spirits quest together (for non-speedy runs) OR the ele can solo the quest! (if you really want a fast time; the Assassin would go back and do the 'Escort of Souls' quest with the Chamber Sin while the Ele is completing Wrathful Spirits.)
Q: How does the ele solo the quest? Especially without Stoneflesh Aura?
A: Ether Renewal

Using Illusionary Weaponry, the Wrathful Spirits inflict 51 armor-ignoring damage each time they swipe their weapon.
However, with Ether Renewal at high energy storage, you can easily outheal the damage they inflict provided you have enough enchantments on you - and spam spells!! (for those not familar with Ether Renewal, you gain health AND energy for each enchantment on you whenever you cast a spell.)
With this build, taking on each group of 3 spirits at a time is no problem. In fact, taking on 6 at once is also doable, but you need to make sure you either (a) constantly spam your skills (burning speed is ideal, since it casts quickly and has NO recharge time) or (b) use other consumables which further increase your health (e.g. Birthday Cupcakes, Candy Apples or Pumpkin Cookies) while still spamming spells.
In addition, I included Ebon Escape in the build to be used at the very beginning of the Wrathful Spirits quest. Before taking the quest, the ele should stand near where the group of 3 spirits spawn 'on the hill'.
When the Assassin takes the quest, an allied spirit will spawn along with the 3 enemy spirits - and 9/10 times the allied spirit is close enough so that you may tele to them on the hill. Once there - immediately spam spells (you should already have enchantments on you prior to warping up there). Note: the enemy spirits will scatter a bit; just wait for them to come back to you and continue spamming.
While the ele is killing the 3 spirits on the hill, the Assassin should run to the nearest 3 enemy spirits below and hex them. Once the Ele has finished killing the 3 spirits on the hill, he may warp down to the Assassin and then continue clearing the enemy spirits.
At this point, both the Sin and Ele may continue killing spirits, or the Sin can run back and do Escort of Souls with someone (most likely the Chamber Sin) while the Ele completes Wrathful Spirits.
That's about it! Hope everyone enjoys this guide and running the new builds!
- DT