I like the concept. I have fun with the build. your guide is ugly though, please work on it :)

I can understand where you are coming from, however, the amount of mana isn't the point, the armor is. Frozen is the best armor for the build- up items. Mana regen is unnecessary because he is efficient with mana early- mid game if you are smart about it (I've never had to return for mana mid- engagement unless I was being stupid). I explained in the guide, you wont be sustaining, you will be bursting down characters and ditching back into the shadows to gank/ interrupt the next champ. He is an assassin after all. As far as the Hex, yes it is a waste of cash, however, so is any other item after your core and inf. edge. Unless you or your enemies are novices, the game will last more than 40 minutes and you will have the cash for the first 5 items. I honestly don't care what the 6th is. It's the CD concept that sustains your damage with skills, play the champ with the build a few times then come help with a more efficient guide.

to be honest, this sucks
you dont need that much mana so frozen heart's worthless, and hextech is just a waste of cash. the best thing you can do with panth is mana regen (chalice of harmony/phil stone) and hp regen to keep you in lane untill level 6.
you sustained damage is also total ****. after your burst your not going to do anything.
really rethink this

also, you have a MASSIVE wall of text with no breakup, work on that to

All of your comments are true and helpful, however, all of this is based on the experience/ knowledge of players on both sides. The saying is true in LOL "If you don't see your opponent, then they're either on top of you or you're already dead." All things come in time; practice, learn, fail. It's okay, just enjoy the champ. You're requests for more advice will come if I learn how to encode icons/ video in this. I am going to attempt to record a game against bots... because they don't gank me while I'm explaining something. If successful, I'll do a PVP vid. As well, you can feel free to buddy me or invite me to a game and I can explain what to do. Pretty much don't be foolish, and be happy you got Warmog's armor.

Well Generally Speaking Its a Nice Build But I feel like if annie Does a Stun On You Or If The Enemy Telports outside Your Ult and outside the range of Ageis Then Your Pretty Much Signing Yourself a Death Warrent Because Most Heros Will ( if they are experinced) Hide In The Grass To Gank Ur ult or Run away. But The Key Thing also is Panthons Ult Hits Them Even if they are INSIDE the grass but you generally wont be able to target them. I Feel Like you should have included What To DO If the enemy Has Competent Players Who Know What they are doing and Know Panthorns Skills And Explaing How To Counter The Effects Of Cleanse And Quicksilver Sash As You know Gets rid of cc and can allow you To Escape The Build With a quick flash out. But it is a good build nevertheless