|When Wolfpack first started working on this mission, the belief was that our forces had to stay on the hill lest the mission end. We had mistakenly assumed rules much like Myth II's The Great Library, in which if you leave the raised foyer entry area before the Codex is retrieved, the game ends and you lose.
It turns out this level is more like Myth II's Through the Ermine, in that you have a campsite but you're not bound to stay in its perimeter. Once this was realized, the LNC outlook for this mission becomes much more possible.
I ended up soloing the mission for a Myth Master Challenge film (in co-op mode of course), but the plan surely would have been better accomplished with a team, and surely is LNCable.
The key is to get off the hill before the south "Trow" wave engages you. By exiting the north gulley and regrouping off the hill and in the northwest, some very difficult engagements are turned into cakewalks.
To accomplish this, I set up two Berserks at the top of the hill's north gulley. In the event the south wave appears before the northeast wave, these two units can rush down the gulley and around the base of the mountain to a spot in the west. They will trigger the northeast wave in this action, but they won't be fatally pursued. In test runs I discovered there is enough time to trigger the northeast wave, kill off that wave, and then get the two Berserk scouts into position before the south Trow wave begins advancing. With the two berserks in position off the hill in the west, the south Trow wave heads for them and not the other units, effectively canceling out the whole wave as a threat because they end up clumping on the edge of a cliff trying in vain to reach the two Berserks.
But none of this panned out in the film. To my great fortune, the northeast wave appeared before the south wave. In this situation, as shown in the film, you just kill the northeast wave and exit the mountain via the gulley and head west without much pressure. The rest is patience: using Archers to pick off enemy ranged units, and then whittle away at a helpless mass of Thrall and Myrmidons. When all that was left of the south wave was the mighty Trow, I had him shot to the point of stoning, just shy of death. It's important to not kill the Trow until the end. That way, you leave an enemy unit alive and in a state where it can be a threat to no one, which gives you the opportunity to scout the map territory and get that "Explore All" law.