Undead have armor that has a 10% chance to reduce damage to 0 (similar to what Heroist had). Tsukiko attacks the undead, and her ability triggers 10% of the time. What percentage of damage will be dealt, 80%?
Next. Ayano also attacks, and her ability triggers 10% of the time. Is Ayano's damage ignored or not?
Added 3 minutes later
If it's just a damage reduction like Jerl's armor, Miko ignores it. But there could be other effects.