Hello there, this is my Pantheon guide! This guide covers both lane (top/mid) and jungle Pantheon.

Mastery Tree 1 - Standard damage build Pantheon, with high-nuke based play style

Mastery Tree 2 - Tanky, early game defensive build, with high sustain play style

Mastery Tree 3 - Jungle build, support-jungle play style

For the first build, it's the standard damage build. It prioritizes high nuke potentials and the damage output will be great if you're doing fine throughout. The second build focuses on a more tanky set-up, thus the defensive items. The third would be jungle build, where you are playing as a supportive-gank jungler.

Skill build 1 - Focuses on getting your W in when the time is right, and E>Q for a damaging combo.

Skill build 2 - Plays a poke, sustain lane, where you max Q first and W in and finish your combo for a kill when you have the chance

Skill build 3 - Jungle skill builds require maxing E for great AOE damage to the jungle creeps and the free 100% crit chance to low health monsters!

Spell set 1 - Ignite-Flash to pick off kills or escape dangerous situations

Spell set 2 - Farm based summoners with poke play styles by maxing Q first either for farming or harassing (For a lane which you have difficulty in)

Spell set 3 - Either Smite-Flash or Smite-Exhaust, depending on which you prefer. Smite is mandatory to clear the jungle faster or attempting to steal Dragon/buffs/jungle creeps/Baron

The route is the standard jungle route. Mainly Wolves>Blue>Wraiths>Red>Double Golems.
Pantheon also excels at invasions due to his ability to stun an enemy Champion. Another route will be Wraiths>Red>Double Golems>Wolves>Blue

I hope you enjoyed this short guide for basic Pantheon play! :D