I think there is a problem with the enemy spawn rate. I battled for 20 min and did not get any variable enemies. No cube, no chest, just blobs.
just explore dude, go find the cube enemy you have to kill to unlock regular fights with it, that thing is how you unlock access to the boss. the little crystals blocking your path all the way to the west give you hints.
the puzzle room is very easy, again, 4 paths, 4 statues. bring all the statues to the start