Bob is invincible until you smash (with Eryx) one of the red circles/nodes on the floor. Bob's face will turn from orange to blue once he's vulnerable and you can start dealing damage.
Eventually Bob will recover and as he does so he'll build up an explosion. This explosion cannot be avoided using evades; you simply have to stay out of its range either by angel gliding away from the center or better yet - a well-timed fully charged Uppercut (Eryx).
After taking out one health bar (he has a total of 3), you'll have to angel lift his eye and enter a battle with a bunch of enemies for a fixed period of time. Once over, you'll re-enter the battle with Bob (2 nodes this time). Take out his second health bar, then enter another battle with some enemies, and then you'll come back to Bob again for the last time (3 nodes).
Below are Bob's attacks. He kindly informs you what he's going to do via the color of the lasers under his head. All of them can be interrupted by smashing a node.
Two green lasers will circle the battlefield in opposite directions. Jump away to avoid.
Three purple lasers will circle the battlefield. Jump away to avoid.
A circular laser wall will emerge from the center. Touching the wall damages you, but some parts of it are empty and safe for you to pass/jump through.
Bob will conjure a huge wall of laser towards you from his mouth. To avoid, keep angel gliding in one direction around the field.
Last updated: 16 Feb 2013