Pantheon has gone through some tough times from patch to patch. The most devastating was probably the time when his stun duration was reduced, which would become a huge deal for pantheon fanatics. But for those who don't know, this would mean that you have to take a more careful aim with your Heartseeker Strike to get the most damage out of it. However, even after that, Pantheon is still a terrifying champion to take on, especially if he lasts through a team fight. Designed as a ganker at heart, Pantheon does just that, and not doing so would be the downfall of any Pantheon player. Learning to play this champion will also teach you map awareness, as you will need it to spot those easy kills

Pros:

Great burst dps
Global ult (while it lasts)
Stun
Excellent harassment

Cons:

Squishy
No escape mechanism
Susceptible to CC

Spear Shot is your bread and butter early game. Its harassment capabilities is alone what enables Pantheon to take mid if he needs to. With this build, mana doesn't become an issue either. Between the Meki Pendant and your runes, laning becomes a breeze. While it does decent amount of damage to discourage the enemies from farming, Spear Shot also excels as a last hitting component to your farming. As I said earlier, mana won't be an issue, so using Spear Shot to get gold is a good thing. This allows you to farm the caster minions without eating any harassment from your laning enemies. Later game, as you gain more attack damage, this skill becomes a nightmare for those with low armor and low health. The spammability of Spear Shot almost gives you a whole other auto attack, only doing tons more damage.

Aegis of Zeonia is one half of the reason why Pantheon is a ganking champion. Even after the patch, the stun Aegis gives you is more than enough to get kills. However, this skill must be used much more sparingly than Spear Shot. Timing with this skill can also optimize your passive ability, Aegis Protection, which will block the next auto attack of an enemy. When charging an opposing champion, Ashe, for example, she will most likely shot one auto attack at you before you can jump on top of her. This attack will be blocked, and once you got your stun off, your passive will automatically be renewed, meaning once she can move, she'll try to hurt you as she runs. This essentially means you eat up over 100 damage early game, possibly over 500 late game, and deal an enormous amount of damage to her before she has a chance to retaliate.

Heartseeker Strike is a great move late game, but early game, doesn't even do enough damage to farm creep waves. This is mainly because you don't have enough attack damage to really do a lot early game, but by later game, you should have more than enough to clear whole creep waves, let along destroy any champion foolish enough to sit in it's aoe. I only get the one stack on Heartseeker Strike simply for it's passive which gives you that confidence in killing a low health champion. Just to clarify, Heartseeker Strike gives a passive to Pantheon called Certain Death, which gives him 100% chance to crit his next auto attack against an enemy below 15% health. As a not-so-important side note, once you've gained some life steal, last hitting minions will be a great source to regain health if you need to stay near an area in case a team fight is about to start.

Depending on your play style, you may like to initiate with your ultimate, Grandsky Fall. This may be only way of initiation for some people, but in my opinion, it's much better to use while a team fight is already initiated. Regardless, hitting as many champions or hitting a single champion is vital for the success of a gank or kill. Timing and accuracy, unfortunately, will come with time and practice, so don't be discouraged if you are having a hard time hitting with your ultimate. This ultimate is also nice during the laning phase because it acts as a teleport and can get you back into your lane in about the same time as teleport.

These particular runes chosen all give Pantheon a much better laning presence early game, giving you a much needed and welcomed advantage for later game. Armor penetration runes, in my opinion, would do much more for you than flat damage runes because it gives you the ability to go through high resistance champs' armor and deal damage, becoming a threat to even tanks early game. Plus, you will be getting so much attack damage from your items, you would be needing some piercing to deal more damage, rather just having it soaked up by armor stackers.

Mana regen runes for both blue and yellow give Pantheon the mana he needs in laning to stay longer, meaning more gold, more experience, and less time it takes to get your ultimate. Again, these were meant to give you an early game advantage so you may farm better and starve the enemies, making killing them a much easier time.

Movement quintessence, while extremely expensive, offer such a huge benefit to Pantheon. Having one of the highest, if not the highest starting movement speed, gives Pantheon the speed needed to reach his target and throw his spear, as well as to get his stun off. Not to mention, being he is rather squishy, it makes running away from hazardous situations much easier. Once again, HUGE laning advantage for Pantheon because being able to catch up with enemy champions to throw your spear makes you a much more annoying presence to deal with as well as making it tougher to lock you down when trying to gank you.

Being a rather squishy character, Pantheon can be easy to kill if you let yourself get focused. It doesn't help that you'll be one of the largest threats on the team, so it would be nice to be able to slip out of dangerous situations. Ghost is a universal summoner spell that can be used both for getting away and for catching up with someone. Using Ghost at a proper time can make a difference between a death and a kill. Blink, however, has more of a defensive nature behind it. Being that Pantheon doesn't have a very good escape mechanism, Blink would make certain death situation to a miracle escape.

I believe masteries are self-explanatory because going into the offensive tree, that offers the most benefits to attack damage carries, gives you an extra boost for your moves as well as work with your runes of penetration.

Starting off with the Meki Pendant seals the deal on your mana issues early game once you have the runes. It also makes getting the Tear of the Goddess much easier, which is a crucial item for Pantheon. Getting a Sapphire Crystal would give you more spammability early, but once you've depleted your mana, it will be much longer to get it back. Spending the rest of your gold on the 2 health potions give you the ability to eat the harassment you were unable to avoid from farming.

By the time you reach level 6, if you haven't recalled at all, you should have enough gold farmed to afford both the Tear of the Goddess and Boots of Speed at the same time. Going back then gives you the ability to buy these items then return to your lane with the least amount of experience and gold lost. Keeping that in mind, it is imperative that you avoid an early game death because that would force you to miss out in both farming and experience (obviously). Once both items have been purchased, laning will be even easier because you can harass even more and even easier with the mana and speed boost.

The next item to buy is the Manamune, which is something you will need, but you won't have to rush to get. At this point in the game, farming should be easier for you and you should be looking around for a gank whenever your ult is off cooldown. Prier to and after getting the Manamune, be sure to keep spamming your Spear Shot as much as you can, for this will get you over 200 attack damage with this as your only attack item.

Getting Infinity Edge is a great item for Pantheon because of that Certain Death passive you get from the Heartseeker Strike, making an attack on a low health champion just that, Certain Death. It also is one of the highest attack damage items in the game, so getting it on a attack damage champion is almost common sense. Building towards the Infinity Edge depends on game to game. When you are doing real well, you will want to start with the BF Sword, giving both your Spear Shot and Heartseeker Strike a huge buff. In games where you are real iffy and you may not be having the best farm, getting the pickax is a better starting item. This is because it still gives you the buffs to your moves which should be able to help you in both farming and killing champions. Only on the worst games ever would you ever want to get the Cloak of Agility first. Getting the other attack item second is most preferred, but you should be able to stand getting the Cloak if you have no other choice.

In my opinion, as well as a lot of yours' I'm sure, the Bloodthirster is the highest attack damage item a player can get for a attack damage champions. Not only will it get you a huge buff for your moves, it give you life steal, which is essential late game in team fights to keep you alive when you're not being focused. I like to get the vampiric scepter first because it gives me that life steal for the reasons mentioned above.

By now it should be late to very late game, and, if played right, Pantheon should be able to solo the best of their team, if he has the jump on them. Through the success of recent experimentation, I found that the Gunblade makes an excellent item for Pantheon because it makes that nuke you have in Spear Shot and gives you enormous amounts of health back. The active it gives you also makes a great utility for catching up to potential kills.

I would like to leave the last item up to you, the reader, because to lock someone into a rigid build that is supposed to work under all circumstances is an insane idea. Knowing that there is a slot open to adaptation will make this build a lot more effective. The best use of this blank spot is something that will undoubtedly make you tankier. Whether that be a Thornmail, Warmogs, Force of Nature, or even a Frozen Mallet.

This is begging to get trolled now, but trolls will always be trollin'. But please, only constructive criticism. It's my first guide and I would like to know what I need to add in for future references