Ok, so I was messing around and found something really weird.

Here is the command:
/effect @p 4 1000000 255 true

You would expect it to give you a really high mining fatigue effect, but nooo...

Basically it is WorldGuard. If you try to destroy a block, it breaks, but then reappears.

Wait, what?

I'm not kidding. And then if you right click with the item you destroyed it with, it restores the durability.

????????????????????????????????

I have literally no idea why this works, but it is great. Except for some downfalls...

One downfall is, if you break a block that takes only one hit to destroy (torches, redstone, etc.) it doesn't work.
D:
Also, if you clear the effect, it breaks a random block that you "destroyed" and drops it as an item.

This isn't really meant to be used much, but I just found it really strange.