Sculk Shrieker

A sculk shrieker is a redstone block found in the deep dark biome that summons a warden when a player is detected nearby.

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

Breaking
Sculk shriekers can be mined with any tool, but hoes are the quickest. It drops 5 experience when mined without Silk Touch.

Post-generation
A sculk catalyst has a 1% chance of generating a sculk shrieker on top of a sculk block.

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). After the shrieking ends, all players in Survival mode within 40 blocks are given the Darkness effect for 12 seconds. Sculk sensors pass on the warning to shriekers only if the sound comes from a player action.

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.

A sculk shrieker has a spherical range of 16 blocks. When a shrieker is activated via redstone power, if there is a player within 16 blocks, the shrieker is activated; if there is no player within range, the shrieker does not activate.

Spawning wardens
Each time a 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 three times, and a warden still spawns on the third 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.

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, and it does not spawn a warden. The player's warning level still increases by 1.

If a sculk shrieker is placed by a player or generated via a sculk catalyst, the tag is set to false, and therefore a warden is not summoned by that particular sculk shrieker.

Trivia

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