This will be for a long time supposedly part of the Daily Quests. But it is very hard and very conditional, so most people won't gain the activity-bonus when this is a requirement.
It again has two stages.
The enemies are tengus and feleses, and they appear in great number.
The good news is, the bosses have low amount of cards.
The first stage is simple: have good damage, be able to stand on your feet - heck, most of the times your regular deck for this point will do.
The second stage is stunning for the first time, and very-very problematic every time. The initial problem is, in each line, right on the heroes, is a row of Heroic Tengu. They must be disposed immediatelly. This demands Backstab and Vigilance, but beware: these tengus also have Backstab ability just to get on your nerves. So backstab rules, as well as Direct Damage from skill-cards.
After disposing them there'll be most of the time 1-2 turns calmness- but that's just the silence before the storm. The AI will play out all of its cards in just a couple of turns, so you better not try to rush in - you won't be able.
Better strategy is to accumlate cards, and when things get in reach, destroy them without letting them hit you (at least try). Feles and werewolves work excelent here, but all races have their cards too. Keep in mind that most of the opponents will be Flying, so you'll have to have a healthy amount of fliers too.
If you manage to clear just one row, and send in some Heroic thing (preferably cavalry), then you'll just have to keep on your feet to win. This won't be an easy task still, as the boss have like a hundred HP.
The enemy will have 2 special cards: a Totem buffing attack, and Chief Hafhnar, who makes situations ultimately dangerous.