OK so this is my first build but I think its good just try it and see. It's a well balanced build between life steal, critical strike, attack speed, and damage.Pantheon is my main champ and I have played with him many times and I have tried many different builds so I have chosen this build because I think its pretty good.

So about my runes. I have chosen runes for critical strike, attack speed and armor penetration. You can also take some runes for damage instead of runes for armor penetration.

So about my masteries I have chosen a little bit anti-carry mastery and if you want you can get some tanky mastery if you but some skill points on armor and magic resist.

So first you will Doran's blade, Berserker's graves, Executioner's Callind, Youmuu's Ghostblade, The Bloodthister and Phantom Dancer then you sell Doran's blade and Berserker's graves and buy Infinity Edge and Black Cleaver.

If you have to play against hard tank like Rammus you will need more armor penetration you have to get Last whisper Instead of Executioner's Calling.

If you want to play tanky Pantheon you have to buy Thornmail and Frozen Mallet instead of Black Clever and Executioner's Calling.

So I have chosen this skill sequence because spear shot is the second most powerful Pantheon's skill but it has little cooldown and its pretty powerful so that's the reason why spear shot reaches level 5 first. Heartseeker strike is the most powerfull skill of Pantheon but it has bigger cooldown than spear shot and that's why it reaches level 5 second. And Aegis of Zeonia reaches level 5 last because it's using ability power and the stun is always 1 second.

I have chosen those summoner spells because I think that every DPS needs ignite and I decided to get exhaust because sometimes stun isn't enough to kill your enemy so you need something to slow your enemy and recharge your spear shot and if you have enough time your Aegis of Zeonia.