You'll need 190 gems to unlock this level.
The Toad Brigade is scattered all over Magikoopa Keep. In this case, it is best to ignore the Toad Brigade and reach the top of the tower without them, as they are a huge liability with Magikoopas attacking you. Grab as many coins as you can, especially around the tower's grounds. Use the green pipe to reach the first floor. Blue Toad is towards the front side of the tower, by the wall. Take the green pipe around the corner to the second floor, pick the plants to the right for coins, then go left. Pick the plant for the key, then toss it on the fan. Go through the yellow pipe and move the fan up so you can grab the key. Also use the fan to reach more coins. The key unlocks the door Green Toad is behind. Go through the red pipe to the fourth floor, drop down to the P-Switch, then go through the tunnel, collecting the many coins inside. Go back to the fourth floor, then through the blue pipe. Walk behind the green pipe to find an invisible Gold Mushroom. Take the green pipe to the top of the tower. Use the plant with unlimited turnips to defeat the Magikoopas. This will make the center part of the tower rise up, revealing Yellow Toad. Now that the Magikoopas have been defeated, get the Toad Brigade, then drop down to the clouds below. This will let you inside the tower for a lot of coins. When you're ready, go to the top of the tower and take the elevator for four to the Star.
Special Challenge: Collect 240 coins.