The Barong and Rangda dance enacts the eternal conflict between good (Barong, the mythical creature) and evil (Rangda, queen of demons). It isn't a performance for tourists — it's a religious ritual still practised actively to maintain the world's spiritual balance.
You can watch a tourist-context version (Ubud, mornings, ticketed). With patience, attend a real temple odalan (temple anniversary). Check the Balinese calendar — these are public, free, and require sarong and full respect.