Mission 73: Defeat Heartless in the Games
Enter the Games being held in Olympus Coliseum and eliminate all the Heartless.
Phil desperately needs Roxas to fill in as a contestant in the Games. That's great news for Roxas, whose mission is to defeat Heartless in the games.
Enter the Coliseum and speak to Phil. He's desperately in need of a challenger for the Games and Roxas fits the bill. You must survive five rounds in the arena, culminating in a battle against a powerful boss.
The first round pits Roxas against a couple of Air Battlers (which should be cannon fodder by now) and a Sky Grappler. Inflict severe damage to the Sky Grappler by knocking the barrels into it from the top of the platforms on either side.
In round two there are several cannon Heartless on top of a wall that can only be hit by the barrels that are lined up in front of Roxas. Knock the barrels into the cannons mounted on the high wall to eliminate them. Notice that the Ordeal Badge for this mission is located behind the wall, so take a lap around the ring before destroying the final cannon. revisiting this mission with High Jump lv.3 allows you to jump on to the wall and fight the heartless yourself, a good idea, as they drop rare Ankharites when defeated.
Use Fire spells to dispatch the Snowy Crystals and hit the barrels at the Switch Launcher. The latter's projectiles teleport Roxas into the center of the arena with the snowy crystals. Avoid its shot by using Air Slides or well timed Dodge Rolls.
Use Thunder spells to eliminate the Watchers as quickly as possible. If Roxas gets inflicted with shoe-glue, use Panaceas to recover. You can't afford to be a sitting duck for the Ice Cannon. When only the cannon remains, ascend to the high platform and use Fire spells to weaken it for the kill.
Round five pits you against a single Stalwart Blade on a flat arena. Stay on the defensive.
Just like with the challenges from Mission 61, use a keyblade with the least amount of combo hits such as Zero Gear to make it easier to use the barrel. If you have Crown of Guilt++, however then you won't need to complete the main game to get Zero Gear as this mission is better suited for magic, than normal combat when compared to Mission 61 and it can also move a barrel in two hits. Filling all the additional gear slots with Magic Units is recommended. For your magic make sure to include Thunder magic, Blizzara, Fire, and Aero at Lv. 5 to help exploit elemental weaknesses (you will need a lot of casts, particularly with Fire and Thunder magic). As Cure cannot be used, stock up on Elixirs to handle healing and restoring magic casts.
In the first round use Fire or Thunder magic on the Air Battlers. For Sky Grappler freeze it first with Blizzara, then strike it with Fire to cause additional damage. In the second round knock the barrels carefully to defeat the cannon heartless. Alternatively if you have High Jump LV. 3, you can get this down quickly by jumping up to their platform and exploiting their elemental weakness with the appropriate magic attacks. For the third round, lock-on, jump, and use Fire to defeat the enemies. The only real hassle is making sure to dodge Switch Launchers' attacks to avoid be transported where it and the Snowy Crystals are. As long as the Snowy Crystals are there it puts Roxas at risk for getting frozen which can waste time. Alternatively, after defeating the Snowy Crystals, use the barrels or attack Switch Launcher directly with regular attacks to beat it quickly. For the fourth round, quickly defeat the Watchers with Thunder magic, then the Ice Cannon with Fire, and just like with the Snowy Crystals, make sure to avoid getting frozen. For the fifth and final round, attack Stalwart Blade with regular attacks until it gets ready to use its charge attack. Block it with Guard to knock it down, then bombard it with its weakness Aero until it is defeated.
Overall, as this tournament has no major bosses, matches should go by pretty quick as long as you take advantage of your opponents weaknesses and know what you are doing, and it also shouldn't be too difficult to get all 3 Challenge Sigils.