It's been more than one year since "Pokemon GO" arrived to mobile devices, taking the world by storm. The game recently celebrated its first anniversary, and with it, Niantic announced the arrival of Legendary Pokemon via the Pokemon Go Fest event in Chicago.

Now, however, the four Legendaries that players have come to know will be making their way back to the game until August 31. Players can now set out to capture Lugia, Articuno, Moltres, and Zapdos, Legendary birds who appear at Gyms as Raid Battle bosses. As always, players will have to defeat them to capture the Legendary Pokemon.

According to Gamespot, these four Legendaries are now available via Raid Battles and will be available through August 31.

Mewtwo arriving at the game soon

Aside from Lugia, Articuno, Moltres, and Zapdos, "Pokemon GO" is also set to receive another Legendary in the form of Mewtwo. However, Mewtwo will only be available through Exclusive Raid Battles.

Another report by Gamespot revealed how Mewtwo was first released via the Pokemon Go Stadium event that took place in Japan, where players were awarded 52 premiere Pokeballs if they took down Mewtwo, The Verge reported. "Pokemon GO" players from all over the world will now be able to get their hands on Mewtwo as long as they participate in Exclusive Raid Battles.

How to take part in an Exclusive Raid Battle

In "Pokemon GO," Exclusive Raid Battles work slightly differently from the typical Raid Battles. According to BGR, those who want to participate will need an invite. But how does one get invited to such Raid? First, players must have completed a raid at the specific gym where the Exclusive Raid Battle will take place.

Such invites will indicate the details of the event. Aside from Mewtwo, players should also look forward to the addition of other awesome new Pokemon from Raid Eggs. For now, players can get their hands on Mewtwo through such events.

Raids aren't as easy as players think

Serious "Pokemon GO" players may already know how to get in and out of raids and reap their rewards, but for casual players, it's not as easy as one may think.

In fact, Mic reported that Legendary Raids are more difficult for casual players because getting such Legendary birds require more time and effort, things that really dedicated players can give to the game. Nonetheless, Niantic has extended the appearance of four Legendaries in the hopes of encouraging more players to set out and capture them. Lugia, Articuno, Moltres, and Zapdos will again be available until August 31.