Htaedsirean

Htaedsirean is a very creepy and frightening music disc that has a broken record appearance like Disc 11, with many colors in the middle.

How To Pronounce
Tae-ser-een

Summary Of What Happens
You hear ambient sounds and a scary theme. footsteps, you hear sounds of Endermen, Zombies and Herobrine. you cough up blood and stop for a minute. you hear static mesh and then you hear them attacking you.

Or is there a way?
To craft Htaedsirean, you need 5 other music discs: 11, 13, and the less threatening Cat, Blocks, and Mellohi. You also need a single diamond, an Ender Pearl, 1 Enchanted Apple, and an Eye of Ender. ​​​​​​

To fully get, it would then require:

Getting a skeleton to kill a Creeper 5 times or more, or get the Discs some other way.

Collect 1 Diamond from wherever.

Kill 2 Endermen.

Going into a Nether fortress and killing a Blaze.

Finding an Enchanted Apple.

Trivia

 * If you try to decode the name, it spells "Death Is Near"