Has anyone actually beaten Megafort Oosten

I'm level 13 and can do about 6000 damage per normal shot but I still am doing no damage. I tried it last night and I managed to get one wall down which was already half health for some reason. And the defenses do so much damage.

So overall it has a ton of health and almost one shots me with my max level tank build.

I think it's impossible to do without an amazing team