Ninjas are the whole point of Ninja Warz. You can recruit them by going to the Recruit A Ninja building. As you buy them they get more expensive. Their stats are balanced. If you want a power suited ninja, if the power is 50, then the health is 40 (usually). Same goes with health. 49 = 41, 42 = 48 and so forth. Occansionally there is a slight better ninja with stats like 51 power and 41 health or 40 power and 52 health. They usually cost more than the ninjas around them. Also, there are achievements for buying ninjas. One for 5 of the same blood type. One for 5 ninjas suited for power and one for 5 ninjas suited for health, and one for 5 balanced ninjas. There is one for universal donors means getting ninjas with O- blood type and universal recipitents which means 5 AB+ blood types