Got to phase 3 yesterday with the dks and one quest is a serious pain that should not be multiboxed.

Basically you have to go into a cave and on the ground around the area are 6-7 i think, runes that you have to click to kill elementals chasing you as they will keep spawning.
Problem is with one solo toon you will have say 5+ elementals running for you, but with 5 toon thats 5+ for each toon you have and they just keep growing, you just cant kill them because more will spawn..it gets crazy and damage gets crazy, you cant stop running to heal everyone or your screwed, they knock you into pools of lava to.

I wiped a few times and then just took one toon in at a time and it was fairly simple.
one rune is at the back you have to time a jump from a wind vent thing to jump across.

Also had a collection quest where you have to collect 20 eggs around the area..not so bad as they give 1-4 e eggs.
I went shadow wardens btw.

But still 4.2 quests have been pretty good.
Only this and the bird quest i hate.