Racial Enemy Against
Increases damage done to the noted enemy race by a specific percentage, and reduces any incoming damage from that same enemy race by a percentage.
Racial Enemy comes with a specific percentage boost in damage, which is simply multiplied into the damage modifier. For all units currently possessing this ability, this boost is 50%. The reduction in incoming damage is a third of the total damage (i.e. 100 damage dealt, 33 is ignored via Racial Enemy).
This means that any unit with the ability will have a 50% boost to all its damage rolls against units of the enemy race and a 33% reduction in incoming damage from attacks of that race.