realistically speaking , the map is pretty easy untill the 3 or 4 liches apear at the end and as someone pointed out , having a mr tank like another valk or horace placed behind your main duelist/princess (again , placed after you set your main duelist , so the lich take aggro) will take the heat of your front line duelist. That combined with 3 healers should be good enough to keep them alive. I would suggest a claudia because of her skill that gives extra mr , but if you lack her , get any dulist with high mr and preferably hp and keep in mind that you can use lightning rods (aka , 1 duelist doesn't have to tank the entire battle. Do it as we did it on immortal beast : swap stuff out if they die. ALso you could use a heavy with high hp to tank them as well if you don't have any duelist capable of tanking 3 liches.