I wouldn't advice doing this on level 24 or 25 u will do about zero damage. Make sure one guy in your team has an arc sniper rifle for Knight shields. One guy with solar sniper rifle for wizard shields. And stock up on ammo synthesis from the gunsmith. The way we did it was camping in the entrance room 1 person stays in the room before where the shrieker spawns. 1 aggro mobs and then try to kill them in the shrieker room. The shrieker spawns randomly and disappears after a short while, when you kill it it releases purple flare things that might kill you.