The plan was simple...
Take the Advanced Heaven Shrounding Plate and activate it to hide their movements. Stay away from the direct line of fire and observe the situation from afar. Find a hole in their defenses, there would be some due to how hectic the situation is, and once it is discovered, use that to infiltrate the city.
Once they're inside the city, they must find an inauspicious spot to set their temporary base. They must make sure to hide their movements and be extra careful because everybody would be on high alert. Once their guard was down, blend in and re-establish the presence of the cult in this city.
Really, they have all the means to achieve their goals. They've been given sufficient supplies to ensure the success of the plan. They were careful all the way through and so far, nothing went wrong.
