Not Updated For Current Season
Sorry for my bad English.
I prefer this build for Pantheon, as it works really good to me.
1) As you see you have not lifesteal, but you have 40% critical chance, that means that every 2nd or 3rd attack you will make about 1000 damage to your opponents. So with 5-8 physical strikes you kill a champion.
2) When you have the first 6 items, you should sell the Doran's Blade as you don't need this now, and buy The Black Cleaver for more Damage
3) Now you are realy unstoppable. So you should buy and the three elixirs. Every time you are doing recall you should buy these.
I suggest you choose Exhaust cause you can exhaust someone when you are getting down with skyfall, and generally it's a little worthless than stun.
I suggest you Ghost for escaping when you have less HP, and for quick supporting to the attack of your team.
You could try also Clairvoyance or Ignite than Exhaust.
I tested this build first time when i see a video with a really g-g-godlike Pantheon with 41 kills! I tested this, and it works.
Thanks for reading.
Sorry for bad English.