How to Start Mission 20
You’ll receive this mission from Captain Cyllene after reporting to her during the previous mission, “A New Day Dawns”. Volo will offer to assist you with searching for the elusive Legendary Pokémon in Hisui.
1. Meet Volo at the Heights Camp
Depart from Jubilife Village and choose the Heights Camp at Obsidian Fieldlands as your starting point. Upon arrival, go over and chat to Volo who’s standing near the back.
2. Visit Grueling Grove
Volo will suggest visiting Grueling Grove, which is located at the north-east corner of the fieldlands. From the Heights Camp, you can glide most of the way north-east on . For the rest of the journey, you can ride on Wyrdeer or climb up somewhere nearby to continue gliding.
Your destination is the small lake/pond at the east side of the grove. When you arrive, an alpha Pokémon will suddenly attack you.
Against this alpha, Rock-types are recommended both offensively and defensively. If you’re aiming to defeat , Rock moves will squash it flat. Otherwise, if you’re trying to catch it, weaken it with non-Rock moves.
Once you’ve dealt with the surprise guest, you’ll receive the Stone Plate.
3. Speak to Cogita at the Ancient Retreat
That’s all the help Volo himself can offer. Next, he recommends catching up with Mistress Cogita. Assuming you’ve got nothing else to do, exit the Obsidian Fieldlands, back to Jubilife Village. Then depart again and, this time, choose the Ancient Retreat, towards the north-east.
Cogita will be inside her house/tent. During your conversation with her, you’ll receive various hints of where to find Legendary Pokémon. For each hint, a new mission will be added: