Go the road and use switch:

Now we must good arrange chests on white sqms(to move chest, stay next to it and click right mouse button, we cant walk slant!), if we do it correct so click green chest and fight with Boss (he got 5mln HP), but if we fail in arrange chest click red chest and do whole quest from beggining !!!!(so be careful!):


Rooms and Bosss are 12!, every next stage is harder and every next Boss got 5mln HP more then last and attack more! (last can attack 320k!!).
After kill last Boss click chest and take your prize.
I upload a few ss how to do some rooms: