think i found a bug: use all your ninjas to connect them to 2 ninjas. every time you connect this 2 ninjas with themselves they will restore a bit of hp. ou can actually heal much of the hp of your ninjas in this way
Level 15:
_________
____ |
| | | __
\ / | ( )
\ / | (__)
| | | __ __
/__\ | ( ) ( )
________| (__) (__)
__ __ __
( ) ( ) ( X )
(__) (__) ( X )
__
( )
(__)
Hope the Picture helps to get 3 stars. the X is the one you have to do last.
If it helps, + it!
 "Pocket Ninja"){kind=icon}
 "I Wanna Win!"){kind=icon}
 "Red Remover Player Pack 2"){kind=icon}