I was recently running HOR and I have confirmed this works in both heroic and reg. When the Lich King event begins you can run ahead of him and behind the pillar next to mountain. If you wait he will walk past you and begin to spawn adds. Once waves are down there is two ways to get loot. 1. Have someone begin running as soon Sylvannas n as says something to the effect of "hurry the tunnel is closing" or 2. Wait till the gunship downs the wall and the Lich King despawns at which time you can walk through. This makes the difficulty of this event for the under-geared MUCH easier. Hope my noob self was able to help.