The Blood Ninja is a promotional unit costing 90 Nanopods, similar to the Ninja Trooper and Shinobi, but far more powerful in combat. It was released as a limited-time unit for the weekend of July 26, 2013.
In addition to higher stats in general when compared to the other ninja units, the Blood Ninja also gains access to a Freezing Strike attack that freezes the target, and a Deadly Shuriken ability that inflicts hefty Poison damage. Furthermore, many of the common "Ninja" attacks are enhanced; the Blood Ninja's Flash Strike attack has a Fire DoT effect and a very wide area of effect, while the Three Stars Shuriken attack does far more damage. Also, most attacks have greatly boosted critical hit chances, as well as a high critical hit stat growth.
The Blood Ninja has a slight resistance to -type and -type damage, but takes increased damage from -type and -type damage.
Note: The Blood Ninja's damage only increases at Ranks 3 and 5, for a total damage bonus of 10 (20% More Damage) by Rank 6, as opposed to the usual 25 (50% More Damage) that most other units enjoy. Also, the upgrade gold costs are significantly higher than any other unit in the game - over 7 million gold to promote to Rank 6.
The Blood Ninja is the third unit to have a Poison DoT attack with a critical hit chance higher than 0%. The other two being the Imperial Hunter and the Bullfrogs.
The Blood Ninja was the only unit to have attacks capable of inflicting every status effect currently in the game ( Fire DoT, Poison DoT, Stun and Freeze) until the Weapon Technician, which introduced the Explosive (400% Explosive damage) and Shatter (400% Crushing damage) status effects.
When viewed from the front, the Blood Ninja is holding his sword in a fencing type fashion. However, when viewed from behind, his sword is not visibly in his hand.
It appears that the Blood Ninja does not have any elbows.
It is interesting to note that this unit seems to have very high Gold costs for promoting, over 900,000 Gold for just promoting this unit to Rank 2.
If using the Weapon Technician, the Blood Ninja's Flash Strike can deal 304-336 (x3) with no crits at Rank 1; Electric Strike can deal 704-736 (x3) with no crits at Rank 1; Freezing Strike can deal 212-236 (x3) with no crits at Rank 3.