Elder guardians spawn in three specific sections of an ocean monument. Their purpose is to protect the treasures of the monument (gold blocks and wet sponges) from players, until the monument has been fully conquered. They also prevent players from simply mining through the monument walls.
Elder guardians attack by sending out a large laser beam which will harm a player, and also inflict the Mining Fatigue III status effect. In addition, elder guardians can target and damage players who are riding in boats. However, once a player is out of range, the elder guardian's laser will disengage and stop dealing damage, similar to a regular guardian.
Once every minute, an elder guardian will search for players in a 50-block radius who are: not afflicted with mining fatigue, afflicted with a level of fatigue that is lower than III, or whose affliction will wear off in less than one minute. Any players who are detected will be inflicted with mining fatigue III for five minutes, and a ghostly image of the elder guardian will appear to a player, with a unique sound. The elder guardian will inflict mining fatigue III even through walls, but will not deal any damage.
Elder guardians do not swim around as much as normal guardians. However, they will act in the same manner as a regular guardian when on land. Their eye will follow and stare at any nearby player, always locked on to their target. This makes them the only mob with dynamic eyes. An elder guardian's eyes are actually the "head" part of the model. A typical mob's head will turn and look toward a player, but with an elder guardian, they appear as though the eye is looking, instead.
Elder guardians are very resistant to melee attacks when they are underwater since players will not be able to quickly approach the elder guardian due to the water's slowing effect. Elder guardians will swim away when they are approached by a player it is targeting, and the elder guardian will deal of damage every time it is hit when its spikes are extended. If cornered, the elder guardian will usually extend its spikes and fire at a player even at point blank range.
Elder guardians are resistant to fire damage, but if they are somehow brought onto land, they can take fall damage from their swift movement sometimes.
If a player must fight an elder guardian in melee, they should either try to corner it and hope for the best, or try to trick it into swimming within melee range repeatedly. The elder guardian cannot shoot as fast as a player with a bow can, so a skilled player will be able to shoot the guardian and then hide in order to break the beam's lock before repeating this process until the guardian is dead. If the elder guardian is in shallow water, then players can use a fishing rod to pull it out of the water, so they can then kill it with melee without being shot at or damaged by the spikes.
The elder guardian has a very large amount of HP (80), which makes melee attacks even harder. Elder guardians also do more damage than regular guardians. Fighting elder guardians is incredibly dangerous without armor. Entering their territory without armor on will almost always lead to a swift death, even if one is armed with a sword or a bow and arrows. Also, a player can use a combination of 2×1 pillars of any material, since the elder guardian laser can't destroy blocks, and doors to get close to the elder guardian, have some shielding from lasers, and have an air pocket to ensure one doesn't drown while fighting the elder guardian.
- The elder guardian ranks 2nd health-wise out of non-boss mobs, secondary only to the iron golem.
- The elder guardian is the first mini-boss mob to be introduced into the vanilla game. However, on Pocket Edition, it is actually considered a legitimate boss.
- The elder guardian has a similar look to the original guardians, with the exception of it being larger and its model is photo-negative, meaning that its colors are inverted.