First of all hello :).
Here is some feedback:
-I like your runes they combine resistances with damage nicely.
-I think you Summoner Spells are good,but Exhaust could be a better choice compaired to Ignite since you are playing glass cannon Pantheon witch means that you have enough damage to kill you enemies already.
-Ability Sequence is good
- Phantom Dancer is generaly a bad item for Pantheon.You pay too much for the attack speed and Critical strike chance is not a stat that you should be investing at.It can be swapped for something much better I believe,and I think in your build a Banshee's Veil would fit in there nicely.
-You haveno boots in the end?.Or you made it this way to show that Guardian Angel is situational
-Glasscannon Pantheon is dead.Everyone know how to counter and fight against him and certainly will be a pain in the *** if you go inside the battle with a so suicidal setup.
Take my feedback under consideration and I will vote accordingly.