// Create a Damage Increase effect
// - nBonus: DAMAGE_BONUS_*
// - nDamageType: DAMAGE_TYPE_*
// NOTE! You *must* use the DAMAGE_BONUS_* constants! Using other values may
//       result in odd behaviour.
effect EffectDamageIncrease(int nBonus, int nDamageType=DAMAGE_TYPE_MAGICAL);

NWN2 also has a paramater for racial type which comes after nDamageType. By default, it is set to -1, however if you want a specific damage increase against a specific race it's the place to enter a RACIAL_TYPE constant.