Mission 75: Eliminate the impostor
The Organization impostor has surfaced in Twilight Town. Find him and eliminate him at once.
Roxas is sent to eliminate the Organization impostor in Twilight Town. He locates the impostor and corners them; it is revealed to be Xion. Roxas encourages her to return, but she draws her Keyblade on him. This prompts Axel to step in and the two fight. Roxas screams for them to stop, which distracts Xion long enough for Axel to subdue her. Roxas confronts Axel about the encounter, but Axel brushes it off and walks away, leaving Roxas confused and frustrated.
Collect items near the starting point in the Side Street, then enter the Sandlot. Roxas becomes sealed inside the area with a gaggle of Mega-Shadows. Staying airborne and attacking with aerial combos proves conductive to Roxas's continuing health. Defeat all Mega-Shadows to unseal the area.
As in the previous mission, the impostor's location appears on the map in the lower screen. Strike the person whenever it stops, and pursue it to its next stop. Scores of Heartless appear near the impostor's stopping points. Take out those who stand in the way and look for nearby chests.
After chasing the impostor and striking it enough times, it vanishes and reappears in the enclosed south area. Follow it there for a closing scene.
Just focus on using Limit Breaks as your key strategy here when you face the imposter when you get to Tram Common. First when dealing with the Mega-Shadows in the mandatory battle at Sandlot, attack them until your Limit Break is ready to go and finish the rest off. Once at Tram Common, just find the impostor and focus your Limit Breaks on it. Ignore the other heartless as best you can though your Limit Breaks can kill them if they are nearby the impostor when you use them. As long as you keep an eye on your surroundings around you and your map to know where the impostor is to eventually know when to head to the south area, then you should be fine. It may take some training to get used to it, and don't be surprised if you have to restart the mission if you take too much time.