<p>Night lv.8 (worked for me like a charm), Landworm 10 (people are saying this doesn't work well, but try it!). Ninja Dragon is a champion type. Every dragon gives 10% chance to defeat it, so keep your fingers crossed and everything should be fine. But still, from round 20 up is some tough opponents, so keep all your strongest warriors awake. Good luck! And p/s: Champion type weakness is Black type. My Night crushed Emerald Knight before and Ninja. </p>