WARNING: I am not a god with Pantheon, I play him for fun.

This build is all about being super tanky with lots of damage, the ultimate bruiser essentially. I focus on getting damage first, earlier in the game so that i can farm easier and just in general do what pantheon was created to do. Then i level off and kind of cap my damage (kind of, check items for more explanation) and build more tanky later on to survive those late game team fights. I personally enjoy this build the most, cause i feel like a tank but can still shred carries.

The runes for Pantheon are actually fairly complicated, I don't have the runes for this build currently because I'm a cheap ***. Anyway, I feel that the runes that I have setup would be your best option. The flat reds Greater Mark of Attack Damage are for an up in damage on your spells and autos, the armor pen Greater Quintessence of Desolation is also for that, but goes throughout the game. The blues Greater Glyph of Replenishment are so you can use your spells consistently and do a lot more damage, because that's where most of your damage comes from.

Standard DPS setup as far as masteries. I take the extra damage to minis just for a little more pushing on lanes and/or last hitting minions.

Ruby Crystal - decent starting item, helps you get through your low level skirmishes or ganks. So now at level 1 you've got health, armor, and damage. PERFECT!

Heart of Gold - great item, gives you tons of money in the long run and builds into your Randuin's Omen

Boots of Swiftness - great for Pan IMO, makes his speed around the map and keeping up with runners is no problem + you are always in range for a stun.

Last Whisper - Amazing late game item, and lots of damage for any point in the game. This buffs all your spells alot, because the armor pen works with your AD spells

Chain Vest - You've got lots of damage now and a decent amount of health. Time to tank up.

Negatron Cloak - Time to tank up again.

Bloodthirster - BOOM. Tons of damage and great sustain. (PS: This item is **** until you have it fully stacked. Don't even go into team fights until you have it stacked, unless they are pushing a turret or something of that nature.)

Warden's Mail - You need this item to build into Randuin's Omen

Banshee's Veil - Build this from your Negatron Cloak. Great item, the spells block can help a lot actually and gives good amounts of MR and a little health.

Randuin's Omen - Awesome item, nice amount of health and great armor, with a great use. (try and remember that you have this use}

Offensive Item Options:

Atma's Impaler - Awesome item, even more armor and a little more damage (I haven't figured the amount of damage you actually get from this after all your items, but it is usually the 6th item i choose because i like being even more tanky and not sacrificing that much damage for it)

Infinity Edge - Great item, tons of damage. This is the only other weapon i would switch with Bloodthirster in the regular build, but i take Bloodthirster for the lifesteal and the damage (fully stacked it has more than Infinity Edge)

Bloodthirster - more damage more lifesteal, why not?

Sword of the Occult - a better item to get early game, but defiantly worth it if you're up for the challenge :D

Defensive Item Options

Thornmail - For those pesky AD dpsers

Force of Nature - I would not recommend this item because of the passive of it, you don't need it cause of your lifesteal. However, the movement speed is great and the MR is aswell.

Quicksilver Sash - lots of MR if you need it, and a great use if you're afraid of their CC

Frozen Heart - Not a bad option for armor, keeps your mana up by giving you alot more, and CDR which is really good for Pantheon. This would be the item that i would use if there was a lot of AD on the opposing team, because of the CDR this is a great item for Pantheon