Sculk Catalyst

A sculk catalyst is a block that generates Sculk features around it when a mob is killed nearby.

Natural generation
Sculk catalysts are generated within the deep dark biome.

Breaking
Sculk catalysts can be mined with any tool, but hoes are the quickest. It drops 20 experience if mined without Silk Touch.

Usage
If a mob dies within 8 blocks of a sculk catalyst, it blooms, giving off soul particles and creates a patch of sculk with sculk veins around that location. Blooming sculk can replace blocks in the sculk_replaceable tag, which includes the surface materials of most of the biomes in all three dimensions. If a mob is killed and detected by the sculk catalyst while over a sculk block, it may occasionally result in the growth of a sculk sensor or sculk shrieker.

The means of death of the mob is irrelevant; mobs can die from being killed by a player or tamed wolf, which yields experience, or by any other means, which does not yield experience; any kill is accepted by the catalyst. In addition, baby animals, which also do not yield experience when killed, also contribute to the catalyst. Rather than granting experience, a bubbling charge will spawn where the mob died. The strength of the sculk spreading depends on amount of experience the mob have dropped when it was killed by a player or wolf. Several sculk charges may end up on the same block and merge, up to 1000 experience per block.

If a mob dies and a charge is detected more than 4 blocks from a catalyst, a sculk block has a chance to use 10 experience to grow a sculk sensor or sculk shrieker. A sculk sensor has a 9% chance to spawn while a sculk shrieker has a 1% chance to spawn. However, sculk sensors and shriekers cannot spawn if there are 2 or more sensors or shriekers within a 9×3×9 box with the bottom center of the box centered on the bubbling charge location (or within -4,0,-4 and 4,2,4 in relative coordinates). The Ender Dragon is the only mob that the sculk catalyst doesn't detect.

A player dying can also affect the sculk catalyst, depending on how much experience the player has gathered. The sculk catalyst wouldn't spread any sculk blocks if the player has 0 experience, little if the player has few experience points and varied if the player has more experience. This could make the sculk catalyst as a way to preserve the player's experience points without having to restore all of the player's previous experience. This doesn't work on players with the "KeepInventory" gamerule set to true.

Trivia

 * Currently, sculk catalyst does not respond to the ender dragon's death. However, it is hinted that this might be implemented later.