Easy. I've only completed 4 lvls so I don't know why I'm here, but it's very easy so far. Get max units while defending and kill. (So far, it's just the weakest unit + 2-3 archers)
||R|2,2,-141,0||463,356,100,87,154,0,p,62,116,0,46,304,151,171.6,0,0,0,s,0,0,0,0,111,342,127,106,197,235,p,87,223,255,44|441.45|412|349|469||
Took me a few shots but I finally delivered (quite amazingly too)
||R||p,428,355,1,0,p,286,55,1,0,p,32,345,1,0,p,49,362,1,0,p,67,346,1,0,p,447,368,1,0,p,50,329,1,0,p,409,368,1,0,p,428,382,1,0,p,292,235,1,0,p,62,46,1,0,p,44,62,1,0,p,39,39,1,0,p,286,86,1,0,p,303,70,1,0,p,268,71,1,0,p,302,256,1,0,p,277,254,1,0|426,161,115,47,13,13,p,206,0,0,6,230,368,100,59,181,159,p,0,167,39,50,162,153,145,152,188,251,p,90,172,238,49|150.6|236.3|261|283||
Wow ... I thought I didn't have the gold and had to try again .. look what happened.
 "DuckLife2: World Champion"){kind=icon}
 "Crunchball 3000"){kind=icon}
 "Flag Football"){kind=icon}
 "Crush the Castle Players Pack"){kind=icon}
 "Frontier"){kind=icon}
 "Stick War"){kind=icon}
 "This is the Only Level"){kind=icon}
 "Multitask"){kind=icon}
 "IndestructoTank! AE"){kind=icon}
 "Triangles"){kind=icon}
 "Demolition City"){kind=icon}
 "Gravitee 2"){kind=icon}
 "Vending Machine Champ"){kind=icon}