Mission 78: Vanquish the Heartless threat

Mission 78 in Kingdom Hearts 358/2 Days sends Roxas to Neverland to eliminate a giant Heartless.

Summary
''We've picked up a powerful Heartless reading at Never Land. Find and eliminate its source at once.''

Objectives

 * Defeat the Ruler of the Sky!

Story summary
Roxas goes to Neverland to eliminate a Heartless and discovers that an old foe has been the one causing the trouble in the world.

Mission walkthrough
After Tinker Bell restores Roxas's ability to fly, collect the badges and blazon hovering over the water's surface in various places. Then fly toward the island where Hook and Mr. Smee are busy working to initiate the boss fight.

Challenge Mission
Given that you have to chase the Ruler of the Sky, this mission will take a while, so be patient. In order to nab all 3 Challenge Sigils, you can't attack even once, so bring plenty of Fire Magic (as it is most effective) and Ethers/Elixers to refill them with. Fire works best while chasing it (so you can damage the tail), and Fira/Firaga can be used while it is stationary. As you can't use recovery magic, Elixers are your best bet. The Darker Than Dark+ or Crown of Guilt++ Keyblades work well here, as when equipped with all Magic Panels, they deal the greatest magic damage. Dodge the Ruler's attacks when you can, as since your level is capped at 40, you will take heavy damage if you're not careful.

This one will require a lot more patience as it is more difficult than the last mission as your level is capped at 20 and may take a couple of tries. Auto-Life at LV3 is a key element here. Stock up on Fire Magic at LV5 along with Elixers or Cura. Use a Keyblade key that is good in physical attack, but without any extra combo attacks such as Zero Gear. Raising your critical attack will also contribute greatly for this mission. Just like the mission above avoid the Ruler's attack as the damage is worse in this mission and heal only when it is safe to do so. Also keep an eye on the map to avoid an out-of-bounds area or making sure the Ruler does not enter it. During the first part use regular attacks or Fire to deal with Ruler's tail. When it glows from entering its berserk do not come into contact with it to avoid heavy damage. Fly low while it charges and do not come into contact with the Ice orbs as it knocks Roxas upward, putting him more at risk for heavy damage. During the second phase when the Ruler uses its coin shot, after it stops use Fire to hit its core before dodging its coins again. If you are in a spot where the coins can't hit you then keep using Fire. Once its core is fully exposed move in and directly attack it to inflict heavy damage but pull back out of its range before it uses its claw attack and repeat this process until it is defeated. Hopefully this will allow you to defeat the Ruler and still get all 3 Challenge Sigils.