Just came out of a game as Pantheon as I've been playing alot as him lately.
I go 0/21/9, taking Ghost and Ignite. Usually start off with either a Long Sword and build into Ghostblade or sometimes go with Meki Pendant at start and then go off with Ghostblade. I heard rumours Last Whisper is good on him now and I've tried it out. I can't judge so much but it seems to work well.
One thing Pantheon taught me is just how awesome Elixirs really are. =D
GT: Wolfiexe Currently playing - League of Legends & Guitar Hero WoR
The regeneration thing in Utility is completely useless.
When people have to go down the Utility Tree, it's usually with one point in Haste (Improved ghost), two in Good Hands (reduced time spent dead) and one in Perseverance (because the first level is better than the other two).
Personally, I go down the Defensive Tree, but I'm biased. I go 21 on defense with every melee champion aside from Shaco. It's up to you, really, there are many ways to play each champion.
If you want to get the most out of Offense, stop at Sunder (6 armor penetration). Don't bother getting Alacrity (4% attack speed), you'll barely be auto-attacking. Get Sorcery (4% cooldown reduction), instead. Never get Archaic Knowledge (15% spell pen), as you have no magic damage.
Lethality (10% extra crit damage) is sort of useful, but honestly, it won't make that much of a difference and you'd have to go way down the Offensive Tree to get it.
I go 21/9/0 for masteries on my panth and take ghost + exhaust but im playing more of a dps than a tank. sometimes i go full offence if the other team is pretty squishy(able to KO them in about 1-3 Qs or just auto atk them down fast) or i build yomuus and either build into a tanky dps hybrid or a pusher depending on whats needed.
Thats the thing i really like about panth is theres alot of ways to build him and work really well.