Elder Guardian

"... You won’t be able to snaffle up the monument’s resources even then - lurking Elder Guardians will cast Mining Fatigue on you, leaving you unable to heave your pickaxe effectively. You’ll have to seek them in the labyrinth and eliminate them one by one to be free of its effects. Alternatively, milk is a useful antidote - just make sure you pack a few buckets of the stuff!"

- Marsh Davies

The elder guardian is a stronger, larger variant of the guardian that can inflict Mining Fatigue.

Spawning
Three elder guardians spawn naturally during the generation of each monument: one in the top room of the monument and the other two in each wing section of the monument. They do not respawn after their initial spawn, thus there are a limited number of them per world. Elder guardians spawned with monuments do not naturally despawn, although they are removed along with other hostile mobs in peaceful difficulty.

Drops
Elder guardians always drop 0-2 s. Looting increases the maximum prismarine shard drop by one per level, for a maximum of 5. When killed by the player, they also drop 1.

They also drop one of the following:
 * $1/2$ chance of dropping a ( if killed by fire). An additional 0-1 drops are added per level of Looting for a maximum of 4 cod with Looting III.
 * $1/3$ chance of dropping . An additional 0-1 drops are added per level of Looting for a maximum of 4 prismarine crystals with Looting III.
 * $1/6$ chance of dropping neither.

Elder guardians also have a 2.5% chance of dropping a random fish as an extra drop in addition to the normal fish drop. This chance is increased by 1% per Looting level, for a maximum of 5.5% with Looting III. This drop uses the same chances that fishing uses, resulting in a 60% chance for raw cod, a 25% chance for raw salmon, a 13% chance for pufferfish, and a 2% chance for tropical fish.

They drop 10 experience when killed by a player or tamed wolf.

Behavior
Elder guardians do not swim around as much as normal guardians. Elder guardians do not swim away when approached by a player it is targeting, unlike regular guardians. Like normal guardians, elder guardians attempt to attack both the player and squid, but unlike guardians themselves, the elder variant is unable to attack cod, tropical fish, pufferfish, and salmon.

The elder guardian's eye follows and stares at any nearby players, and always looks directly at its target. The eye still follows a player under the effects of a potion of invisibility, but doesn't attack. It seems that their eyes are coded to simply track the closest player, as they also follow players in spectator mode.

The elder guardian has three methods of attack, including firing its laser, inflicting mining fatigue, and a defensive thorn-like attack.

Laser
The laser takes several seconds to charge, doing no damage and allowing the player to move away in the meantime. As it charges it turns from purple to bright yellow (thus acting like a warning indicator). Once charged, the beam abruptly ends and deals damage on normal difficulty. The elder guardian swims around for a few seconds before firing again. The beam cannot be dodged and has a maximum range of approximately 14 blocks. Once the player is out of range, or if the beam is obstructed by solid blocks, the guardian's beam disengages from the player, and deals no damage.

Inflicting Mining Fatigue
"During the development of the ocean monument I had a problem. I wanted the pyramid to feel like a maze, so you have to figure it out to get the treasure, but the bad - and good! - thing about Minecraft is that you can just rebuild everything. So the solution would always be just to knock your way through. And I didn’t want to make the pyramid indestructible because that’s also not fun in Minecraft. So after a couple of ideas we decided to have a boss guardian that would have a spell effect that would slow everything down."

- Jens Bergensten

Once each minute, the elder guardian searches for any player within 50 blocks to afflict with Mining Fatigue III. When afflicted, the player sees a ghostly image of the elder guardian and hears a ghastly noise. The effect decreases a player's attack speed by 30% and decreases mining speed even more, for 5 minutes. A player cannot hide from this attack. It targets players through blocks, even underground, and a potion of Invisibility offers no defense.

The image of the elder guardian is a particle effect that can be recreated by issuing the command.

Spines attack
An elder guardian deals of damage every time it is hit while its spikes are extended. If cornered, the elder guardian usually extends its spikes and fires at the player, even at point-blank range.

Data values
Elder guardians have entity data associated with them that contain various properties of the mob.

Trivia

 * The elder guardian's eye is actually the "head" part of the mob's model, giving the illusion of a dynamic eye.
 * The elder guardian texture has the name "jeb" on it.
 * According to Jeb, elder guardians were introduced to encourage players to solve the temple maze rather than dig through it easily. He acknowledges there are ways around it, but, nevertheless, players still have to solve the challenge in a different way.
 * Also according to Jeb, the "jump scare" by an elder guardian is unintentional, instead he added it to provide a visual cue as to why players get slowed down by mining fatigue.
 * In Java Edition 3D Shareware v1.34, elder guardians drop blue keys.