Magic Attacks that do damage depending on armor amount

Diamond armor needs an equalizer.

PvP is not the reason to play Minecraft, and I stand by this. Who wins and who dies is always dependent on who has better armor, or who attacks first. Thinking strategically doesn't help either, because it can take 10 arrows from even an enchanted bow before the rampaging, diamond armored monstrosities go down. Why can't combat be based on the type of weapon used against certain armor amounts? What if a fireball, thunderbolt, or ice attack could cripple said diamond armored maniac?

Introducing: Magic Attacks and "Resistance vs Defense". The higher the defense, the lower the resistance, and vice versa.

Sure, diamond armor will remain great against physical damage, as it always was. However, magic could give it a new weakness: zero resistance. It will be like going into a sword fight armor-less. This can give players the option to use less-used armor, such as leather, or even chainmail, to account for resistance and magic. Not every situation has to include diamond armor anymore.

In my opinion, the argument that diamond armor should be kept overpowered because of how expensive and rare diamonds are is a terrible one. High-leveled players who rampage around servers stealing and killing will have diamonds in droves, and have no reason to resort to less expensive armor such as iron.