The Raiders base mechanic is Blood. You get Blood points when a Raider attacks an enemy unit (with a normal attack, poison attack or action skill). Assassins (or regular Raiders) can then execute a "finishing strike" with lethality that is directly proportional to the number of Blood points.

Battle phases

• Preparation - the Raiders will utilize their superior speed and sight range to scout for the enemy and determine its weak side.
• Initiation - Raiders will start harassing enemy units, slowing them down in order to allow stealthy Assassins to move behind their back. Ideally, these attacks will build enough Blood points for a series of finishing strikes
• Culmination - the Assassins will come out of stealth, backstabbing the wounded enemy units and finishing them off. Assassins use a finishing strike that is appropriate for the situation, e.g. they could try to decapitate an enemy or just leave him bleeding to death.
• Conclusion - Raiders have an easy time overrunning retreating enemy units. Poisoned enemy troops that are moving at a slower pace are dispatched by Assassins (who can move faster once out of stealth). If the enemy group is too big to destroy in one engagement, Assassins will go back to stealth mode and the Raiders will return to hit-and-run tactics.