Complex sentence: Steenbergen enjoyed the "first-rate brotherly scenes", and was happy that the series followed through with its promise of sending Dean to Hell, commenting that the related hellhound attack was "one of the scariest things the show has done yet".
Split into simpler sentences: Steenbergen enjoyed the "first-rate brotherly scenes", and was happy that the series followed through with its promise of sending Dean to Hell. The related hellhound attack was "one of the scariest things the show has done yet".