My guild is currently struggling on the 3rd door of horridon, because by the time we get to the 4th door there are still a lot of adds from the 3rd door up, and we get overflowed with adds and die helplessly. Is there any clever way to deal with the adds since we can't stack because of the frozen orbs?
Actually you can stack. What we do is mark the tank, have people be as clumped as possible on him and move as a group every time an orb is dropped. Your range can be slightly behind the tank so they don't risk getting a tick before they move.
Doing it like this makes it easy for passive cleave to bring down all the small adds.
We just stack and cleave them down (prio warlords), calling out when a warlord cast frozen orb, then just moving straight away to a new spot, although generally the adds took longer to kill anyway than the first 2 doors.
I think the biggest thing that we changed to make this go smoother was have the horridon tank go to the center of the room so people could see their direhorn. Then by the time he makes it to the 4th door, he's back on the wall past the 4th door. The other thing we changed was the shamans both switched to purge macros from searing totems for their direhorns. After both of those changes we started getting to the last phase every single time.
And as everyone else said. You can stack, you just have to communicate when the orbs go down so people don't take any more than 1 tick from the orbs.
Stack on tank move as you get one frozen orb down... If you have a dk on your setup pop army when you get the third warlord. (make sure to have glyphed so army wont taunt). Dispell always and gg easy door.