Pantheon is one of my favorite champions.One being he looks like a spartan. Two i love his combo (rweq) and able to use spear shot as doing 700 damage with only a 3 second cool down.He is also my main champion. Pantheon is a AD based champ with some other stuff.Pantheon is a champion that uses his abilities not so much with auto attack/right click.Pantheon is mostly played on top or bottom doesn't matter but not mid unless its the only choice.
if u like champions that do massive damage , a easy combo, and want to get kills, Pantheon is the champ for you.

Pros and Cons of Pantheon

Pros
Fun :D
Easy combo (rweq)
Does a good amount of damage(2621 NOT INCLUDING skyfall)remeber that he can use spear shot many times so the damage can go up to 3??? in 8 seconds
Aegis Protection(Passive)
Able to tower dive
Has two passives Aegis of Protection and Certain Death both useful

Cons :(
Mana Hungry
Cleanse is one of Pantheons counter
Nerfed ( Skyfall no longer whole map range Spear shot base damage reduced)
When you use his W u will be in front of the enemy and so u have to aim ur Hss ( Heart Seeker Strike just right)

I didnt mention this but Pantheon will be buffed in the next patch along with Garen Nasus etc....
Those are all the pros and cons of Pantheon i have found so far

The reason i chose armor penetration ad runes and some cool down runes is because Pantheon is a AD champ so able to use his full potential you'll have to get behind your enemy's armor and do more damage. This also help with tanks that stack armor. AD runes are kinds obvious of why i chose them (Hes a AD champ) no brainier? I also chose cool down runes because you will be able to redo the combo if your enemy does not die from the combo or heals. Also the reason i chose runes that give more output at lvl 18 because obviously ranked games will be quite long and you will be at lvl 18 so you will have a better potential then and there no point of have a rune that gives less than half of the lvl 18 rune that only help begging game.

OK now most Pantheon guides/build are all the same items but, mine has some differences .
first start of with the Long sword. when you hit lvl 6 or u need to heal up again you should buy the brutilizer if u have enough money if you don't have enough ( which i don't know why) go kill some creeps/champs if you are able to) and get the money). if you find out that u are getting many kills you can switch the brutilizer with a sword of occult for more damage.Next would be a yoummus Ghost blade ( Tip you should make a key binding for this easier to activate.) Next is a Manamune it is a perfectly fitted weapon for pantheon it has mana which pantheon needs because he is mana hungry and it also gives his damage at the same time.Next is a B.F. sword/bloodthirster because it give 100 damage at fully stacked and 60 when not stacked.After that is a last whisperer. this gives some damage and armor penetrations which is what pantheon needs. after is a frozen mallet the reason you get a frozen mallet is because lets say a enemy uses cleanse then u wont stun them but, since u have a frozen mallet they will be slowed so u have a chance to get back a little more so u can use spear shot or kill those running champs. last is a hex tech gun blade the reason i got this is because it has spell vamp AP and AD pantheons w is a 1 ratio for ap which boosts it slight and also giving u little more AD which is also good. If you do not want to get the HexTech the alternative is a Infinity Edge for 80 DAMAGE and 25 critical which can help pantheon since if he got a critical it would be 1000 damage which is also good.

So overall Pantheon to me is a tier 2/1 champ after the patch. he is a fun champ and is very useful in team fight and soloing backdoorers due to his skyfall and soloing champs.This is my first guide/build so i hope its useful if somethings need to be changed fell free to leave a comment. -Pantheon out