// Create a Damage effect
// - nDamageAmount: amount of damage to be dealt. This should be applied as an
//   instantaneous effect.
// - nDamageType: DAMAGE_TYPE_*
// - nDamagePower: DAMAGE_POWER_*
effect EffectDamage(int nDamageAmount, int nDamageType=DAMAGE_TYPE_MAGICAL, int nDamagePower=DAMAGE_POWER_NORMAL);