This is a very simple "don't stand in the fire", tank n spank encounter with a new gimmick called "sound". Every time you take damage from his various fire attacks, you gain sound.
If your sound is maxed out (the icon flashes yellow), the boss will wipe you out with what is essentially an instant kill attack. Most can be avoided, but one, "Modulation", hit the entire raid for a small amount of damage and sound. You get rid of sound by banging a gong on the side of the room. However, there are only eight gongs, and they can only be used once each. The gong will also stun the boss and interrupt whatever spell he was casting.
After a short amount of time, he will take off in the air, and blast people who have high sound with a killer laser. Run around to avoid that, and other obvious fire spots on the ground. He'll land and repeat the cycle until one of you dies.
The best time to use the gongs is once per ground phase, and once per air phase. During the ground phase, he will cast a spell called "Searing Flames" that does massive aoe damage. It's 5 seconds channeled, and you want to make sure you don't take more than 1-2 ticks. Interrupting that spell is key. He also casts "Sonic Breath", a rotating fire "beam" similar to C'thun or Mimiron. This is easily avoidable.
After he lifts off, give the gong a hit to clear everyone's sound, and they should have no problem staying alive until he lands. That gives you 4 ground/air cycles to kil lthe boss, which is more than enough, even with somewhat shoddy dps.
I recommend assigning one person to gong duty; someone that you trust to pay attention to Searing Flames raid warnings. Ranged dps is best for this job. Everyone else just needs to not stand in the fire.