Pantheon is a great off tank bruiser that can dominate that top lane or any lane you choose to bring the art of war to. He has a steady early game with strong pokes and some anti harass due to his passive. Late game is where it gets fun and the damage kicks in and you literally begin to stomp on people upon level 6+. Playing Pantheon can be a little tricky though, in the wrong situation you may not be able to escape. Pantheon is a more of a all or nothing initiate when it comes to battle. Hopefully this guide you in becoming a strong Pantheon player in the Rift.

PROS
Great turret diver

Strong Poke

Blocks for days

THIS IS SPARTA!

CONS

Not a whole lot of mobility

Can fall off late game

Many spells bypass Pantheons passive

Vulnerable to ganks

Udyr is not a very smart match up even though he may not be seen in top lane much he is also a deadly threat from the jungle and would be strongly advised to face him. Tenacity, pokes, and kites are all effective against Udyr if in the situation you must fight him.
Yorick is a known counter to Pantheon and is very difficult to beat and is not advised to play against him. He is mixture of Tank, Mage, and Bruiser all in one with some strong sustain in lane. Pokes with your Spear Shot will not be as effective with Yorick. The more tanky situational items along with hard CC would be a better investment into this fight.
Fighting an Elise as Pantheon can be a challenge and is almost aggravating if they are good enough. Be advised whenever you ult she may just use her Rappel when she is in Spider Form to dodge it and Pantheons passive is not very useful. If you can dodge her abilities and be careful early game you can survive the laning phase.
A fight with Riven can be tricky but she can be beat. Denying her of her farm and staying clear of her early game and abilities will do the trick. Avoid skirmishes and being near her with low health after level 6, but getting Riven caught with CC will clear her out.
As you play against a Renekton you want to be in control and don't give him an advantage. While playing Pantheon poking and not allowing Renekton to come forward is key. With armor penetration your hits will put him out of his confidence when he gets some tank items. But be careful because in the wrong situation Renekton can get to you fast a keep you there.

Jax and Pantheon is always a debated fight and are similar champions in the way that they both can jump and stun. Pantheon on the other hand has more poke than Jax does which is a strong advantage. Though it is advised that you should not go into a head on 1v1 when facing Jax after level 6. But catching him off guard with your ult or stun is a better way to approach Jax.
As Pantheon a Teemo cannot do much as far as fighting you. His darts can be blocked by your passive and Teemo is a relatively squishy champion and your jumps will stomp him out of the game. Do be careful of the blind and mushrooms because they can get you caught in bad places.
With your passive ready and your W up walking up to a Nidalee will get you multiple blocks when she is in cougar form. If Pantheon can get close enough she will be forced into that situation and have to go cougar form. Pushing the lane will put her out of place and cant do much about a Pantheon roam. Do not try to out poke a Nidalee because her Spear cannot be blocked and she most likely has more sustain than you may have.
Gangplank is pretty much one of the worst picks against a Pantheon you can possibly imagine. Facing a Gangplack is real easy, your passive will block his Q every time its up. Out poke him when your passive is up then finish him off when he is low. Just don't get too cocky because that's when you'll screw it up.