Well to be fair you can get well over 13 artifact points at 99. I have 15 and haven't really been farming hardcore for AP. Another player I know of has 22 points.
That said, there is only one class/spec that is actually capable of a literal one-shot; as in a single ability taking you from 100% health to 0% in instanced PvP. From what I saw, it was EXTREMELY difficult to set up. I think he only got it off maybe twice in a single battleground and I believe the damage it does greatly varies. He seemed to not want me to tell anyone about it tho for fear of a nerf so I won't say what class/spec it is. I will tell you it's not a mage tho.
Now if you're talking about taking someone from 100% to 0% within 5 seconds or less, well that's a different story. Several classes are probably capable of that. I know I am anyways (ret paladin). The key is to combine your biggest burst with a mecha blast rocket while berserked. Also, combine berserking with any other damage boosting cooldown. In my case, avenging wrath. Mecha blast rockets are off of the GCD so you can blow someone up pretty quick.