Mission 21: Collect hearts
Roxas continues having flashbacks of the boy in red as he and Axel go on their mission to Agrabah. There, they find Pete searching for a way to the Cave of Wonders and its magic lamp.
This mission is long and slightly difficult compared to the earlier missions. Make sure your panels are stocked before you embark on this mission. Fire magic will be quite helpful during this mission.
Entering at the Palace, grab the surrounding chests and badge, then head down into the Agrabah Streets. Here, you Kingdom Hearts II players will notice a familiar antagonist: Pete. Pete is searching for something, and to discover what, Roxas and Axel must cautiously follow behind. A blue-colored range then appears in front of Roxas. Keep Pete within the blue area as he wanders around in order to move to the next area. If Roxas enters the red-colored zone, or takes the blue-colored section off of Pete too long, Roxas must restart from the beginning. Stay close behind Pete as much as possible and watch his movements carefully. You will do this twice, once in the Agrabah Streets, and again at the Agrabah Gate. Successful completion leads to a new location to explore: the Cave of Wonders.
Snag the loot at the Cave of Wonders, then continue forward. The Entrance Hall requires some rearranging to access what you'll need. First, eliminate the Heartless on the lower level, then head for the crate in the northeast. Move it down to the southeastern corner by hitting it, knocking it towards the short pillar at the end of the platform. Use the crate to hop on the pillar, and then onto the platform to reach the switch. Hop back down and hit both the crate and the golden pillar over to the northwest corner to arrange a way up to the platform there. Destroy the Heartless at the top, then head through the door.
In the Pillar Room, dispatch the minor Heartless quickly then proceed to the Large Armor. The use of Fire magic is highly recommended against the Large Armor. Once the Heartless are defeated, the required portion of the mission gauge will be filled. Either RTC, or continue by pressing the switch in the northwest corner to operate the pillars. Hop up the moving pillars and stationary platforms to the door set high in the northeast corner. Continue through and enter the Abyss.
This new room does not offer much to do in terms of objectives. First set off the switch to the right, then open the nearby chest. Afterwards, jump off the ledge into the dark pit to return to the Entrance Hall. Roxas lands on the upper platforms in the Entrance Hall. Here, there are chests and more Heartless to defeat. Defeating the five Heartless will finish up the Mission Gauge. Jump down and leave.
While you're heading back to RTC, make sure you stop in Agrabah and pick up any chests you might have missed while you were pursuing Pete. There will be minor Heartless on your way back through, but they are Pureblood Heartless and will not add to your Heart Points.
Although the time limit to acquire three Challenge Sigils seems very forgiving, the sequence of following Pete, moving the blocks around the Entrance Hall, and jumping between moving platforms in the Pillar Room will slow you down if you aren't prepared. Be sure you familiarize yourself with Pete's route so you never have to restart an area. The blocks and moving platforms are easier to deal with when you have High Jump LV2 equipped. This way, you can skip moving the crate next to the tall block and also jump on high platforms before they descend all the way down.