Rotastic
12 Achievements
The Ninja
Kill 3 enemies in 4 seconds in a multiplayer game
14.1%
How to unlock the The Ninja achievement in Rotastic - Definitive Guide
Nod Nolan
TrueAchievements
TrueAchievements
I did this in Combat mode, playing with three AI characters, choosing the Pinball level on the 'easy' selection of screens.
The key to this achievement is that 3 Ninjas have to die! That means you must slice their ropes and they must fall out of the play area without recovering. just slicing their ropes isn't enough as they can recover and start rotating on a nother pin.
on the pinball level you have five pins. Top left, Top Right, centre, bottom left and bottom right.
If you slice your enemies ropes on any of the highest 3 pins its is likely they will recover, so it is far easier to use either the bottom left or bottom right pin.
It is a question of luck when all three enemies are in your vicinity, so make sure you always attach to the pin a close as possible so you will always slice their rope and they can't get yours.
It took me about 6 multiplayer games for everything to fall into place and the 3 AI enemies to fall into oblivion in quick succession
MysticWeirdo
TrueAchievements
TrueAchievements
What you want to do is latch onto one of the pins in a tight circle with your main controller. Press on hold A to do this. With the other controllers you'll need to press and hold A for a larger circle on same pin until your main controller cuts through the other controllers line and then let in fall off the screen. Quickly repeat with the other two controllers. The achievement popped when you cut 3 lines in fast enough succession.
smartbomb
As this is multiplayer, you must be playing Combat Mode. Although you can earn this in any type of match on any map, I strongly recommend a game of Jewels on the Pinball Map. Choose to play against 3 AI players and set the game duration to 500 Jewels to give yourself the best environment for the trophy.
You will see that the map has 5 pins, one close to each corner and one in the centre. Rotate yourself down to either of the bottom 2 pins and hold down 
so you are in a constant state of revolution. The AI will all be flying all about collecting the jewels, and once they are all gone, more will spawn. You will constantly snap the ropes of the AI as they try to swing from your pin. Sometimes they will save themselves, sometimes they will fall off the screen and die. This is very much luck based as all 3 AI opponents need to be coming to your pin at the same time. You'll more than likely kill 3 in a row several times but not within the time limit, and there will be times they will attach to your pin in a smaller radius than you and end up cutting your rope instead. All you can do is just stay on the same pin as long as it takes and it will come eventually.
This method is also very effective for the Butcher trophy.
Should you have 4 controllers and 3 other people to play with, then this trophy and certainly Butcher will be much easier to earn. Just synchronise your friends to all swing to your pin in quick succession and cut their ropes for an easy trophy.