This build it not intended to be an 'in-depth' Pantheon build, it's just going to be 'food-for-thought,' or quick cheat sheet as another way to build Pantheon, which happens to be the ONLY way i build my Pantheon, and it has allowed me to easily solo most other pantheons, as well has sustain higher damage levels due to longer survivability. Though it is not in-depth, it is fairly wordy because i like to hear myself talk.

Pros
-Great damage, even for a beefy build
-Beefy, able to stay longer in lane and duel better
-Many items are harmonious with IE without sacrificing other stats
-No stacking items, no fear of loss of stats from dying

Cons
-Not all that tanky, an OFFTANK, NOT a tank
-Not as much damage as a 3+bloodthirster stacking (though you'd always fear loosing them)
-No stacking or snowball items means that you don't have as much potential for damage or health (meh)
-Fairly manahungry, so there is a need for Runes

These are just my favorites on Pantheon, and should not be the absolute way of playing pantheon, just what i find the most helpful, but as a basic rule i always have a mobility spell and an offensive spell. I usually just pick what my team is lacking, though on Dominion it is important to always have garrison AND the mastery in defensive spells, seriously helps in a defensive ult on windmill against a three man capture party ( I end up doing it all the time)
Masteries are a personal choice, but the crit damage is nice since Pantheon has a GUARANTEED CRIT, and a little more to IE is nice. Just be sure to get masteries into summoner's spells if you use the ones that the masteries improve.

I see so many Pantheons not combo-ing right. Your spear shot is one of your main damage moves, lowest cooldown/manacost, but the heartseeker is just TOO GOOD to not level up, so i usually level up these two spells about the same time. BUT the important part of this section is the COMBO: Spear, stun, Heartseeker, Spear. If someone else has harder hitting cc, then save your stun for an important target, like an ulting Nunu, or Malzahar. The point is though, is that starting with the spear allows you to throw another one ant the end of your combo, and if you have Frozen mallet, then hit them once after heartseeker, once before, or both. This is VITAL to play against other pantheons.

Most people build Offtank Pantheon with a Warmogs Armor and Atma's Impaler. I have never been a fan of Warmogs, and only ever buy it on a Dr. Mundo build. Heath regen is fantastic, and heath is good, but needs the armor to back it up. For that reason, i prefer a Giant's Belt item with another add on, specifically sunfire cape, but in the case of Pantheon, I prefer to have a frozen mallet, more heath, additional damage, and an on hit proc that will keep you on your prey. Another reason i don't usually build Warmogs is that i keep my builds consistent, and there IS no Warmogs Armor in dominion (which is the gametype I play Pantheon on the most.)

Manamune is one of my favorite items, but I feel that it detracts you from your goal: beefy damage through IE, Atmas and Frozen Mallet. The potential damage increase and mana increase does not give as much potential for damage early on (which is your prime time as Pantheon, you want to be done by the end of Midgame) However, if you feel you can drop the hexdrinker to get the Manamune, do it, but that makes a VERY expensive core build, and will take you so much longer to get up to offtank speed (would be nice on a pure AD pantheon).

If the enemy team is REALLY getting fed in one category or another, rush that Chain Vest before you get a giant's belt, or drop the hexdrinker slot for an early Negatron Cloak to build into either Force of Nature (if there are multiple fed AP carries) or Banshee's Veil (if there is just that ONE DAMN CARRY with AP) at the same 'phage' stage in the build.

Getting that early Brute will exponentially increase your damage throughout the ENTIRE game. That early Avarice blade (which should only be a problem if you are anticipating longer games) is great for getting you expensive BFSwords and your Frozen mallet, but after that, all of the items are cheaper and the gold comes faster. but it is important that you get frozen mallet and Atmas as your first FINISHED items. THEN get that IE ASAP, and after that is usually when you finish that Youmuu's. This order gives pantheon the best Mid to Late game potential, as opposed to rushing youmuus or IE (which i see too many Pantheons doing).

I like to start with the Doran's just for the health bonus for having the same damage as a longsword. I don't usually even finish my Youmuu's, the gold bonus of the Avarice blade is far too tempting just to lose for an active skill (though it is very helpful). I try and keep my Doran's at least until it is time to get a BFSword or a chain vest for Atma's. When you finish your Atma's, it is usually about time to finish the match (either you are too good, or you can't carry a team of 2 or 3 feeders).

The Doran's as a start has one weakness, the potions you get from starting with the longsword is a lot better in a **** lane then 3% lifesteal, plus, you are that much closer to an early Brute. Though, starting with the Longsword leaves you without the health that Doran's gives, so you are going to want to get some defensive runes. I prefer more health with utilitarian runes (cooldown and regen of both health and mana), but that is because my style has me being more aggressive with my q, and i need the mana, and i prefer regenning in lane to get that extra gold and exp over them.

I personally feel that you should not pay attention to the rune choices. These are the rune sets i use, but i recommend that you just stick with your own runes, mostly because runes most play into the early game phase, and the rune shoice should be based on how you play your champ. Health regen Quintessences are fantastic, but not vital in dominion, i i prefer flat health. If you are a lot more aggressive and worry about early enemy armor, ie: you see a tanky team comp in draft mode, then getting some Armor MR of your own and some armor pen quints.

I see a lot of Pantheon players using earlier versions of my build, befoer i had figured out really harmony between the items. If you look at my current build, almost every item works together, Youmuu's crit chance applies to your IE, the movement speed assists in getting up to someone just out of Aegis range to get your Frozen mallet proc off, the Armor of Atma's works with the health of Frozen mallet, as does the MR of the boots and hexdrinker (one of my favorite items) the passive of Atmas agrees with the health of Frozen Mallet (second best health item [minus snowballs of course]) The crit of Atma's seriously helps the IE. At the end of the game, you with have more health, more armor and similar damage of 'glass cannon' Pantheons (who will never be able to keep their bloodthirster stacks up). If you feel like being more of an arse than you already are, skip the hexdrinker and get yourself a bloodthirster (only if you are confident that you are too hard to kill), but usually i don't get the stacker items and stick with the hexdrinker, one of my favorite items, making you THAT much harder to kill, whilst still giving decent damage.

Initiating SUCKS. Have another teammate initiate, then start your combo on the squishy. Pantheons damage disappears when there are focuses on him, and my build is not beefy enough to take a full frontal assault. Jump in after the fight has started and the cc has been expended, then there is NOTHING to stop you. I am not going to get too in depth in any tactics that i use, mostly because they only work with my playstyle, and you should find your own tactics to fit accordingly.

I start with tier 3 boots and get the mid tower first, then ghost into the speed shrine to get to top before some of the major fighting starts. If you focus your mobility into the middle of the map then you can hit the speed shrines or have access to the entire map with your ult from the centre bushes.

This was not intended to be a full and in depth guide, there are plenty of other guides that crunch the numbers and go into strategy more in depth than i ever could, and I learned from those other guides, but I had made this guide because i do not see any other builds that balances out so well as the build i had developed after about eight months of playing pantheon and thinking "Why don't I add this" or "this doesn't work because of this, so let me try that."

So Thanks for Viewing my Build
-Sincerely,
Gamma028