It took me ages to complete this mission i'm an ele monk
lolz
but now i farm it all the time earning about 5 k per run in cores and cloths of the brother hood.
heres how i do it.
ok 1st off always use ur delver title to get healed whenever u cast a spell on the destroyers. Always have alkairs alkmedial acid in your skills you can get this by doing some eazy quests for high presit alkar.
ok theres two ways of doing this mission noob way and pro way.
noob way is slower but you are more likely to pass the mission and get the cloth.
pro way is faster and you only do this when u have a good group and want to get on the leader board.
when glints doing with heroes u do it noob way 1st find some one and get em too add there heros.
you take left side they take right, the left side is harder on the second spawn so u should take that as u cant trust the other person, they could be a noob lol.
after the second spawn go back and stay reazinably close to dragon because dolls spawn on the dragon in the 4th spawn.
keep defending the left and right entrances untill the bosses come then one of u take u and ur heroes to the left and one of u take u and ur heroes to the right.
try not to aggro too much and good luck farming XD
if your going to do this mission pro way make sure u find some good minion masters and some good monks and a couple of ursain warriors and a water ele spammer. pro way is basically the same as noob way exept u camp the spawns and on the 4th spawn send a ursan warrior back to kill the dolls.
heres the build I use as a WATER ELE
1. Elemental Attunment
2. Glymph of lesser energy
3. Aura of restoration
4. deep freeze
5.ice spikes
6. summon ice imp.
7. alkaris alchemedial acid
8.deft strike
p.s i dont have rez becasue all my heroes have it.

heres a sceenie so u can see the kind of equipment and skills me and my heroes use to destroy the destroyers.
hope u find this usefull and if you didnt i dont mind my main reason for posting this was to make all the bloody fire eles go water, man i hate noob fire eles that think they can kill detroyers grrrrrrrrr they dont get it there 100 dmg fire spells do like 10 dmg agaisnt the destroyers.