Mission 30: Collect hearts
Team up with Xion, eliminate Heartless in Agrabah, and collect hearts.
Roxas and Xion continue their mission to collect hearts. Afterward, they meet with Axel, where they learn that he has retained all his memories from before his transformation into a Nobody. Meanwhile, Naminé and DiZ have made their way to the Old Mansion in Twilight Town.
You'll begin in Agrabah Gate. No enemies will appear, so you can walk around and collect treasure chests at your leisure. Once you are ready, head north to Agrabah Street, where Fire Plants and Loudmouths abound. They are scattered around on all the roofs as well as the ground. Use the crate with the breakable base to reach the high areas if you need to. Take them all out and proceed to the Palace.
At the Palace, a Large Armor is waiting for you, and so is its protector, a Barrier Master. It's the usual drill; take out the Barrier Master first, and then focus on the Large Armor. This may become occasionally hazardous, as the Large Armor loves to hop all over the field while you try and destroy his ally. Once the two are gone, grab the chests around here, and if you have High Jump and Glide, the Unity Badge. Then head back to Agrabah Streets, where two more Fire Plants will be waiting on the ground for you. If you choose to get rid of them, you will fulfill the mission's optional goal. Whatever your choice, you can head back to Agrabah Gate to RTC and end the mission.
This is a very easy challenge, even with the restrictions. It's the same as completing the optional mission as detailed above. An easy 3 Challenge Sigils for sure!