Bal

Bal is a Boss that spawns every 5 minutes in the Khazad-dûm if a player is nearby. Killing the boss allows players to obtain the Topaz Crystal.

Spawning
The Bal spawns about every 5 minutes while a player is within, which can be found randomly generated in the lower Y levels of the Crystal Hollows. Bal will appear in the center as an expanding Magma Cube and the Topaz Crystal will disappear.

Drops
Upon every hit, Bal has a chance to drop items on the ground in the form of dungeon blessings. These items despawn in around 2 minutes. Over the duration of a Bal fight, around 25-40 items will drop. These items can be:

Behavior
Bal will hop towards the closest player, summoning Fire Bats and Blazes to attack the player when hit, and shooting fireballs at an interval of once every hop. In addition, it will deal contact damage that pushes the player away like a normal Magma Cube, although the knockback can be avoided with a resistant item. These attacks deal low damage, with the Fire Bats and Blazes ignoring the player if they have an Intimidation Artifact or a Parrot Pet.

When an item is dropped, there is a chance that Bal will summon Fire Bats or Blazes.

Upon being defeated, it will teleport to the middle and slowly shrink, before disappearing. After that, the Topaz Crystal will appear nearby.

When alive, it makes loud slowed enderman angry sounds, which can be heard from a medium distance away.

Upon hitting Bal for the first time

 * You cannot best me!

Upon Bal dropping an item

 * Grrrr! You won't be able to hit my Fire Bats!
 * Bah! Come forth my minions! Fly above, take them out!

Upon defeating Bal

 * AGGHHHHHHHHHHH!

When Bal is about to spawn

 * The ground starts to shake and the lava bubbles...

At 75% health (50 damage dealt)

 * The bosses outer shell looks to be weakening!

At 50% health (100 damage dealt)

 * Half way there! The boss is starting to become weaker!

At 33% health (133 damage dealt)

 * Nearly there! The boss is shaking it can't last much longer!

Upon defeating Bal

 * The boss looks weak and tired and retreats into the lava...

Trivia

 * His health is displayed as.
 * The Bal is based on the Balrog from J.R.R. Tolkien's Lord of the Rings series.
 * Its spawning place, Khazad-dûm, is also based on the place of the same name.
 * It used to be possible to trap Bal by building a cage around its spawn point, but building in Khazad-dûm is now restricted in order to prevent it.
 * Unlike the Ender Dragon drop mechanic, a Bal pet drop is public, allowing anyone to pick it up.