Developer Niantic has announced Pokemon Go’s next major event: the Ultra Bonus Event. And this one will help anyone find rare Pokemon.

Before we get into the event, on 13 September at 1 pm PT, trainers worldwide will have the chance to find three legendary Pokemon originally exclusive to the Kanto region. Niantic said Articuno, Zapdos, and Moltres will appear in raid battles until 20 September. You might even find them in their shiny forms. Pokemon originally discovered in the Kanto region will also appear in raid battles until 30 September.

So, to be clear, Articuno, Zapdos and Moltres will be at gyms worldwide for legendary raid battles, including their special shiny versions, from 13 September, when the Ultra Bonus Event starts, until 20 September. Then, once they leave, Mewtwo will come to raid battles for the first time at 1pm PT. According to Niantic, Mewtwo was previously only been available to trainers invited to EX raids.

Now, all trainers will be able to challenge the legendary Psychic-type Pokemon until 23 October at 1pm PT. Lastly, Farfetch’d, Kangaskhan, Mr. Mime, and Tauros will join the Alolan Pokemon in 7 km eggs through for the rest of the month. These Pokemon, which were regional exclusives in Asia, Oceania, Europe, and North America, can help you to achieve a complete Kanto Pokedex.

This Ultra Bonus Event follows several summer Pokemon Go events Niantic held this year, but this one may be the coolest of them all.