This is a guide for Mass Outbreaks in Pokémon Legends Arceus (PLA).

Also known as “Swarms”, Mass Outbreaks are increased sightings of Pokémon that sometimes happen. They will start appearing around the time you enter the Crimson Mirelands, perhaps sooner.

How to Identify a Mass Outbreak¶

The game is quite clear when a Mass Outbreak is occuring. When you use the Front Gate of Jubilife Village to head to an area, Ress the gatekeeper will warn you that there’s a Mass Outbreak somewhere.

On the world map, there will be an icon of the Pokémon at the heart of the Mass Outbreak inside one of the areas. Then when you’re inside the area, that Pokémon’s icon will be somewhere on the map. Naturally, you’ll want to fast-travel to the location nearest the outbreak.

Upon reaching the outbreak, a message will appear along the top indicating you’ve discovered the outbreak. Initially 4 Pokémon will appear at once. You can make more Pokémon appear by catching or KOing them. After a while, once you’ve gone through a bunch of Pokémon, the outbreak will end.

Benefits of Mass Outbreaks¶

The main benefit of Mass Outbreaks is that they allow you to easily encounter the same Pokémon multiple times. This makes it easy to fill in some of your Research Tasks, for example. Of if you just want to grab a whole lot of Pokémon!

The hidden benefit of Mass Outbreaks is the vastly boosted shiny rate, giving you the greatest chance of finding an elusive Shiny Pokémon. Pokémon in Mass Outbreaks have 25 extra shiny rolls, increasing the base shiny rate to 1:158.

How to Trigger Mass Outbreaks¶

Mass Outbreaks are random events that you cannot directly influence. The only thing you can do is keep returning to Jubilife Village. Each time you return, there is a 20% chance of an outbreak appearing in each of the 5 regions. The chance of at least one outbreak happening is around 67% (when all 5 regions are unlocked).

If you leave a region that currently has an outbreak, there’s a 20% chance that particular outbreak will vanish when you return to the village. However, there’s a way to preserve outbreaks. Before leaving the region, you can save in the region and reload your save file to try again if the outbreak disappears when you’re back in the village.

Pokémon Found in Mass Outbreaks¶

Obsidian Fieldlands¶

Crimson Mirelands¶

Cobalt Coastlands¶

Coronet Highlands¶

Alabaster Icelands¶