Hello everyone, this is the first build im writing for all of you sparta lovers.
After seeing lots of builds for pantheon (which made me giggle) i decided to create the build
that will let u own and kick every damn champion in LoL(with the right team of course). The build is mostly based on the importance of armor pen.
Before i begin, i am sorry in advance for my bad english :]
So lets Begin..

Pros: Cons:
Strong laner UnderEstimated
Super ganker Mana hog
Powerful early game and late Squishy
He can VS any champ 1v1 Hard to understand and master
You need to be a veteran to do well with a gay team

I go for AP marks and Quints, Clarity seals, and focus Glyphs.
AP is a must on Pantheon since a bit of AD doesnt help much cept for early game and not that much+ it works very well with the items. I take Clarity seals because as we all Pantheon fans know, he drains his Mana because he is a great harrasser and has low base cd. I take Cool-down glyphs because Pantheon is just a great harraser and with the Clarity runes he just keeps attacking and laning without tower hugging. The clarity runes lets Pantheon stay in lane longer and harrass without worrtying about his Mana.

I dont see any possibile replacements for the runes, i have tested all the possibilties and these works the best. I guess u can just go average and take armor seals and magic resist glyphs :]

Before the new masteries came out, I would go 9/0/21 (worked best with the build), but since
there are many new options and stats on the Offense tree, i go 23\07 for some very important reason. Ill start with the Utillity tree: I basicly take the mana-mana reg options for some reason, with these and the Clarity's Pantheon is no longer Mana-hoe.
Offensive tree: I simply take the critical 10% extra dmg because of pantheon's passive of HSS.
The cooldown(the more the better :]) and the armor pen.. Your Precious. About the 10% magic penetration.. Pantheon's ult is very underestimated with his dmg, and used more like jumping around the map. With this stat, and right aiming, you can easily take down enemy's hp to half.

Ignite+flash = ultimate pwn
I see only one replacement for Pantheon isntead of ignite.
You can pick Healh if you would like to solo top.

There is a very important rule of pantheon player dont get, he HE IS NOT MADE FOR BURSTING[/u]. Pantheon has low cooldown, and with these runes and Masteries. it will be idiotic to get attack speed items since u use ur skills in between one and another. I saw many build advice the players do max Spear Shot first for better harrass.. this has 20% of truth because u can harras way better with HSS(your main skill use).
HSS is a powerful ganking skill, since u can stun u just penterate the *** of the enemy with ur APs.
For ganking or initiating i would stun first>use HSS>and then ignite+spear shot.
On that point ur enemy has about 40-60% hp left.

Doran's Blade- I always start with this items for the Hp Pantheon needs and the dmg
that makes ur harrassment more powerful+life steal is always good.
BF sword- with this item on early game(u shud get it before 20:00) ur AP stats works best.
Last Whisper - at this point i dont think i need to explain why (with this item stacked,
there is no tank in the world cept for those has 5khp+ that Pantheon would not scare them.
Mercury boots - pantheon is squishy and has a lack of Magic resist..
These can be replaced by Ionian boots Depends if they have lots of AP champs.
Blood Thirster- Extra AD and Life steal helps u lane longer.
Now to the defensive items that turns u From squishy to a Deadly Off-Tank:
Randuin's Omen- This item gives you the armor def you need to play against strong AD carry, Extra cool down, and extra Hp that helps ALOT+Hp reg.
Force Of Nature- This one give you extra Magic resist to defend against High AP champs,
high Hp reg that works very good with ur life steal and helps ur stay in fight longer.

Pantheon is known as Anti-Carry, of course he is very powerful against carrys
but with this build, you turn into a penetrating machine cuz no one can stand against 50% armor pen+ 30AP+300+AD.
You get the right defense you need, NO MORE MANA PROBLEMS!, and you just get more intimidating just as Galactic Renekton in action.