Sculk Shrieker

A sculk shrieker is a sculk block found in the deep dark biome that produces a 'shrieking' noise when a player is detected nearby. Shriekers found in the deep dark can summon the warden when they are triggered.

Natural generation
Sculk shriekers can be found within the deep dark biome. These shriekers can summon the warden.

Breaking
Sculk shriekers can be mined with any tool, but hoes are the quickest. It drops 5 experience when mined without Silk Touch. When a sculk shrieker is broken it loses the ability to summon the warden, even if mined with Silk Touch.

Post-generation
A sculk catalyst has a 1% chance of generating a sculk shrieker on top of a sculk block. These shriekers do not summon the warden.

Usage
Sculk shriekers can "shriek" after being activated, which can happen by a player stepping on it or triggering a nearby sculk sensor. The shrieker shrieks for exactly 90 game ticks (4.5 seconds).

Sculk shriekers have a 10 second cooldown per player. This means that if a player triggers one shrieker, they are completely unable to trigger any other shrieker within 10 seconds. The cooldown period includes the 4.5-second shrieking, which means 5.5 seconds after the previous shrieking ends, the player can activate sculk shriekers again.

At minimum, a sculk shrieker has a spherical range of 16 blocks. If there is a player within 16 blocks of a shrieker when a nearby sculk sensor is activated, the shrieker is activated[needs testing]; if there is no player within range, the shrieker does not activate.

Spawning wardens
Sculk shriekers that naturally generate in the Deep Dark biome are capable of inflicting the Darkness effect upon players and summoning wardens. If a sculk shrieker is placed by a player or generated via a sculk catalyst, the tag is set to, and therefore a warden is not summoned and Darkness is not inflicted by that sculk shrieker. Each time a naturally generated sculk shrieker is activated, it adds 1 to a "warning" level to alert the warden. The warning level is specific to each player, not each sculk shrieker, meaning that the same player can activate a different sculk shrieker for each of the four times, and a warden still spawns on the fourth activation, even though any particular shrieker had been activated once. If a player does not activate any sculk shrieker, the warning level decreases by 1 every 10 minutes (12000 ticks). After the shrieking ends, all players in Survival mode within 40 blocks are given the Darkness effect for 12 seconds.

When a player's warning level reaches level 4, the sculk shrieker attempts to spawn a warden after its shrieking ends, or immediately if the player breaks the shrieker. Up to 20 attempts are made to spawn a warden within an 11×13×11 box centered on the shrieker. If there isn't another warden within 48 blocks, a warden emerges from the ground.

If the player that triggered the sculk shrieker is outside the shrieker's range when the shrieking ends, the sculk shrieker does not apply the Darkness effect to any player. The player's warning level still increases by 1.

It is possible to make a warden spawn from a safeish distance by shooting a bow into the direction of known sensors that are near shriekers. The sensors can be seen to activate and the warden warnings can be read from subtitles. Eventually a warden spawns. This possibly means that arrows launched by dispensers can do the same.

Trivia

 * The sculk shrieker's design was inspired by the human.