User blog comment:Crimson Storm Mich/Future Units Preview v2/@comment-27619228-20170209150205/@comment-2061246-20170210162718

Critical Damage Resistance and Critical Chance Resistance both multiplicatively affect your modifiers, not additively affect them.

If the boss has 100% Critical Damage Resistance, then that means your 500% Critical Damage Buff is actually 0%, not 400%.

If the boss has 50% Critical Chance Resistance, then that means your 60% Critical Hit Rate is actually 30%, not 10%.

Therefore, a boss with 100% Critical Damage/Chance Resistance will negate all Critical Damage.