The easiest way we've found to deal with the devour/floral trap phase does not include the briar at all. The person who gets the yellow light bulb stays directly behind the Raf, the rest of the party heads in front of him (don't worry he doesn't cleave during this phase yet). As soon as the light bulb disappears from that persons head they run directly through Raf. The person running will get stunned for a second, but NOT devoured. After the stun wears off Raf will do Spit. This is when the entire party moves back behind the boss to avoid the cleave when he spins back to face the tank.