Ni no Kuni walkthrough, Part Thirty-Four: Skull Mountain
With a de-powered Mornstar in hand, Oliver is partway to his destiny of eventually trouncing Shadar… but without the complete wand, he won't be able to defeat the Dark Djinn. He needs the three gems that will power up the Mornstar, and a Sky Pirate has the map. How annoying.
Your next destination is Skull Island (which, if you've been doing Bounty Hunts, you've already visited). Sail north of Castaway Cove to the northwestern edge of the Summerlands to find the beaches leading to Skull Mountain. The enemies here are appreciably stronger than back in Hamelin, so be on your guard.
Enter the cave at the top of the slope. The group will come across something rather startling hidden inside: a massive airship, no doubt filled with Sky Pirates. Save at the waystone hidden beside the ramp, then cross the gangplank to the airship. You'll be stopped by Kublai's men - but when Kublai himself appears and notices the Mornstar, he invites everyone aboard. Lucky!
Kublai is willing to listen to the story, and is even willing to entertain the idea that Oliver might be able to beat Shadar. He needs to test the boy first, though, and he calls down his Red Dragon to do it. Boss battle!
If you're lucky, this battle can be an absolute joke. The Red Dragon is powerful, true, but it's weak to poisoning - and will be stunned if you manage to land poison status on it. Every time. Take advantage of this by using Swaine's Rot Shot over and over. Should the percentages land in your favour the Red Dragon will not only be stunned, it will take several hundred points of damage before recovering itself. Manage to land this three or four times, along with normal attacks, and it's toast. Ice attacks work well against this beast, and Defending, as always, is quite effective in warding off its strikes.
Kublai will acknowledge your prowess after the battle, mention something about a queen, and stalk off to his cabin to get the map you wanted. The map reveals the location of the stones Oliver needs to find, but they're on an island Kublai's Iron Wyvern can't land on. He has a dragon to lend you which might be able to help - only the dragon, Tengri, is feeling a mite under the weather right now. You'll have to bring him back to full health first.
Tengri is sitting in a part of the cavern you haven't yet explored, and you can see it from the deck of the ship. Head off of the ship - talking to a sailor on the lower deck for some alchemical formulae before you debark fully - and use Nature's Tongue to talk to Tengri. The dragon can't quite describe what's wrong, though the solution is obvious enough to everyone. His soulmate in Motorville is in a bad way. Yikes. You'll have to do something about that.
Head up onto the deck again and talk to Kublai. He'll tell you to get right on finding a cure - and give you a Jumbo Sundrop to help out. How kind. He'll explain final evolutions for familiars (which you may have already discovered on your own) and give you alchemical formulae for making more evolutionary stones.
That's all for Skull Mountain. Use Gateway to zip back to Motorville and find a cure for poor Tengri.