Can't play the map atm. Judging by the look, lighting wise, it look to white and to uniform (same brightness, colors). For example, you have red and blue lanterns, they are supposed to emit red and blue lights. Try to stay away from white lighting.
There is a bit to much of bloom.
Fog should be a bit more dense since there is a lot of humidity & water particles in the cave.
You can make the map look better by adding contrast using a postprocess volume or adjust those by the worldinfo parameters.
Nice use of stock assets
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Stevie's corner A blog dedicated to UE4, UDK, UT99 / 2004 / III / 4.