This build was initially made in season 12 adcs were in a bad spot, that's why some of the text is ****ting on adcs.

Although this guide is from a couple seasons ago i'm still updating the build as I change my playstyle.

Are you not tired of playing jinx, kai'sa or other adc's which get oneshot or can't deliver damage during the earlier stages of the game? Then pantheon is the right champion for you.

While his kit might look simple you actually have some of the best all-round kits for the botlane. You have a short cooldown wave-clearing Q which also works as a poke tool with slightly larger cooldown. You have a gap closing W, which while empowered also works as a burst tool.
To add on, pantheon has the best deffensive ability in the game in his E, since he can block all damage as long as he's facing the source. Finally, an ultimate which allows him to roam early, tower dive half to low hp ennemies and in later stages dive the unaccesible backline for a quick oneshot.

If adc is not your thing tho, you can absolutely demolish with this build on mid.

As a sidenote I believe this build should work up to masters.

To put it simply pantheon is not an adc, he is a mid/top/support/jungler, that's why it works, adcs are bad this season, that's why you are playing this in the botlane, however as you see the build is a bit unconventional, he is building items an adc builds while not getting the attack speed to deliver the damage to tanks or bruisers. The thing is that when you play him you will understand that you can burst anything in the game as long as you have empowered W. Which is basically 3 empowered very fast autos and a stun. This makes it specially deadly if you build on hit items like Bork and kraken's.

Blade of the ruined king (BORK): This is the core of the build, you should always buy this first.

-Navori: Works really good mainly because of the extra ability damage and lower cooldowns. If you feel fancy you can go Infinity Edge but the damage iutput will be the same but without getting the extra cd.

The Collector and LDR/Mortal Reminder: Always buy both. I tend to buy collector first. However, If the enemy team is on the tankier side I suggest buying a serrated dirk and delaying collector to buy LDR or Mortal reminder, taking advantage of serrated dirk early spike but having a better time against chunky opponents.
The main benefit of buying this two items is that at the end of the game you get 65% Armor pen And more or less 20 lethality which greatly amplifies damage against tanks and gives you almost true damage against any other thing.

Boots: Since galeforce removal pantheon has been effectively cut down on his pick potential against ranged targets when he doesen't have flash, therfore, we compensate the lack of galeforce buy building swiftness boots.
Pantheon in my opinion has always had a problem with boot choice since you should always be blocking most of the enemies damage with your E with my setup, therfore making tabis or mercs less valuable.
That being said, boots should be delayed if you are able to consistently hit your ults or have the ability to effectively manage your combos for your E move speed. Sometimes all you need is jumping once on the opponent to kill him especially if you are ahead, therfore having an extra item or good component instead of boots is worth.

Finally we have the flexible slot. The last item you get is for adaptability to the enemy comp. If you are stomping buy bloodthirster(BT). Against 3/5 Ad? buy Frozen heart. 3/5 ap? buy maw of malmortius. Pantheon has the unique ability to wield almost every item effectively, he is kind of a Jack of all trades, however refrain from buying anything ap that is not a zhonyas. When Full Build sell boots for dead man's plate, this item is great because you still need move speed and it provides some damage and resistances on top of that.

A full build should look like this. In this order from left to right.

BORK > Collector > LDR / Mortal reminder > Navori > Flex slot > Boots / Dead man's plate

This build lacks defensive items because, if played well, this build allows for high damage (almost one shot combos), and fleeing with your E which cancels all incoming damage.

The fist rule is to not overextend and use tap Q to farm since the cooldown early is about 5 seconds. If enemies dare to zone you early on just jump on them, they are not able to outdamage you since you have one of the best lvl 1-3 possible.
That being said, the key to a healthy earlygame is not being afraid of loosing a couple minions as long as you stay in xp range.
To add on, if the enemy has ghost be especially careful since they will outrange you without the chance of youbeing able to counterattack.

If you don't get kill before lvl 6 it your lane will be harder, but you honestly kind of deserve it since you should have abused more.

Before min 14 you should be aiming to take as much platings as you can without destroying turret. If you destroy turret you are giving enemies a chance to farm from a safer spot and you can overextend and get caught. If you get caught, enemies have no stuns and you have ult up use it to escape.

It will honestly depend on what you have achieved so far in lane.

-If you managed to get almost all cs and 1 kill you should be able to buy pickaxe and tier 1 boots.
-If you don't have enough gold for the former get boots + vamp sceepter or just a pickaxe.
-If no kills and you were pushed out of lane just try to salvage anything.

Generally I like starting any fight with at least 3 charges of passive, If you are below 3 you can either auto anything (this goes from wards to jungle plants and minions) or start taping Q onto the air (try not doing this in early game too much since you will lose a lot of mana). Then at 4 charges you can start the combo with Q empowered W auto auto empowered E. Or if at 5 charges you can either do empowered W auto auto empowered Q (if you think you can kill the target with that combo) or empowered W Q auto empowered E.

Empowered E is a great gap closer since you will move faster towards the objective at the end of it's duration. Therefore, you can also Start with Empowered E for a quick catchup then W Q and finish off the target.

A small tip would also be that if you want to take advantage of your Q's execute propertie below 20% hp don't hesitate into throwing in one more auto or igniting the enemy early in the fight instead of using Q right away.

Another fight starter can be done while having 4 charges of passive and walking up with E if you think the enemies are going to waste important cooldowns on you, then W onto someone, auto him 3 times and you will have empowered Q to finish off a taget. If the taget is not dead yet and his team is close try leaving the fight momentarily.

Another way to fight is to flash, w (empowered) onto someone, which should be unreactable, and 3 autos + Q. Then leave with E.

To finish off unsuspecting targets you have the unreactable combo of Tap Q flash. Your Q can be buffered so this interaction is amazing since it gives you a ton of range.