In the Denpasar and Ubud areas, you'll find a number of local groups performing a variation of the Barong Dance. Your guide will find one for you.
The Barong is a wicked-looking Balinese figure, a God of sorts. But he needs to be that mean in order to destroy the truly evil gods. It's a mix of history and mythology (as everything appears to be on Bali).
The story, according to legend, is that Rangda, the mother of Erlangga (Balinese king in the 10h century), was condemned by her husband (!!!!) because she practiced black magic. After her husband died, she summoned all the evil spirits in the jungle to come after her son (Erlangga). The black magic troops were so strong that Erlangga had to ask for the help of Barong. Barong came to the battle with Erlangga's soldiers. Rangda cast a spell that made Erlangga soldiers all wanted to kill themselves, pointing their poisoned spears into their own stomachs and chests. The Barong casts another spell that made the soldiers' resistant to the sharp spears. In the end, the Barong won and Rangda ran away.
Accompanied by the banging and clanging of the Gamelan Chimes (called Gongs by the locals), it's a magical experience that should not be missed!
You'll be surrounded by tourists, so when you set up your visit (with your hotel or your driver), try to pick a time (early in the day) when the crowds are smaller. Trust me, you want to GET CLOSE to this performance. The closer the better!
Warning: if you don't take the time to read up on the basic story, it will just be colorful noise: lots of jumping, yelling, and acting out. But when you understand the story, you'll catch a critical aspect of the Barong character. He's a BAD DUDE: bad-looking and bad-tempered. There's nothing nice about him at all.
And if you need to defeat pure evil, you better have a REALLY BAD DUDE on your side!