Invasion is the 14th Expert floor in Monkey Ball and Super Monkey Ball, and the 23rd Expert stage in Super Monkey Ball Deluxe. It also appears as the 133rd Ultimate stage with continues, and the 173rd without.
The whole floor is fairly thin. However, the board on its own would be very easy (save for the very thin, straight part right at the end). The reason this stage is tough is because it is littered with bumpers, some stationary, and some dynamic. Without good timing, precision and steadiness, this floor can eat lives in challenge mode.