Beat Box

Since nobody here seems to have pointed it out exactly, I'll provide a helpful hint for the first phase.

When you first spawn in, keep a mental note of which side of the room you teleported to. When he does [spell=229215], dodge the patterns but try to stay on that side of the room if possible. The last pattern before [spell=229578] is the one I kept messing up on, since every square in the room gets electrified in short order. However, there's a single safe spot, and it appears to always be the same location: between where you spawned in and where Beat Box is positioned in the center of the room. Get to that square quickly and you can move on to the second phase (or, as mentioned in other comments, cheese your way past it).

The only comments I could find on the fight failed to mention how to do that last pattern, so I hope this helps!

I'm not sure if it was just luck, but I managed to cancel the second phase by interrupting its second cast, [spell=229578] (I just used a Disorient spell).
After what he'll just stand there, doing nothing while the public tells you how great your moves are.

Note that you can also stun him at the beginning of the fight when he cast [spell=229215], but he'll recast it anyway.

Beat Box (B3@7 B-0X) does [spell=229215] as the first phase of the fight. You need to dodge a sequence of electrical patterns on the floor, i.e. one half covered, second half covered, middle free. Afer you complete the sequence Beat Box will start casting [spell=229323] and you will get ported to one of four (4) dancing circles around him, the camera angle will shift focus and you will view the arena from above, you will begin to dance and be unable to cast any spells or use any abilities.

Time to show off your [spell=229578] in this second phase! You now have to collect and dodge orbs to both deal damage to Beat Box and avoid damaging or killing yourself. Use the arrow keys to move between the four (4) positions (up, down, left, right). Collect as many light orbs as you can and avoid all the shadow orbs. Each collected light orb deals damage to Beat Box and every missed light orb deals damage to you through [spell=229585]. Collecting any of the shadow orbs kills you. After a short period of time you need to start dodging [spell=229215] again to get back into collecting orbs. I hope your levels of funk are sufficient!