Today, Jay wanted me to experiment with some powered creepers using his spawner. We came to the sick idea to face a level 10 powered creeper.
I found a level 10 creeper and I powered it using a lightning knife. Afterwards, I caught it with an empty spawn egg. Finally, we both went to my home, spawned it and let it explode right in my face.

Note that before the explosion, my valkyrie armour set had just been repaired, so its durability was completely full.
After the explosion, these were the durability values of my armour:
Helmet: 296/363
Chestplate: 462/528
Leggings: 418/495
Boots: 355/429
Gloves: 451/480
Note: my armour has protection IV and unbreaking III.
I hadn't lost a single heart, but as you can see, it damaged my armour pretty bad, considering my armour also has unbreaking III.
Conclusion: Never even dare facing a powered level 10 creeper without highly enchanted armour, it would most likely be the last thing you'll see before the explosion.
So now, just imagine yourself in a natural situation. Rain, stormy, so lightning strikes now and then. A group of 3 level ten creepers is standing there. You feel like attacking them, but are too lazy to go get your armour because you're sure you can kill them using your long reach with your valkyrie axe. Right before you attack them, lightning strikes on them, making them powered. You manage to hit them a few times, but just then, they explode right next to you. There goes your axe (if you're not premium V)! And IF you were wearing your god armour, well, I suppose it wouldn't be there anymore with three of those ultimate monsters.
I hope this is a good lesson for y'all adventurers out there.
This was definitely a fun experiment.
~ Rob.