The BC changes pretty much gut Pantheon's laning
Now, no AD caster particularly like bonus AS from Youmou, but Pantheon particularly hates it. See, if you taken Riven or Talon for example, they benefit from the AS and the minor increase in crit because they will be autoing a LOT. Pantheon does not do this. In fact, his main incentive to use attacks is simply to get his shield up. However, if he doesn't need his shield, he is going to E then Q with maybe 1 auto if the enemy is just about to die with a crit Q. If the enemy won't die to Pantheon with that or can flash/dash away Pantheon does not engage. Now you'd think this would be great with Youmous. Now he can get in that extra auto before they escape.
Except by the time he gets youmous, skirmishes have started, 1v1s are a thing of the past, and he needs that 200 health from BC to help him get beefy with all the insane armor he gets passively. Yes it makes a difference. Not to mention Youmous has shit AD for someone who pokes with Q primarily. The AS, crit, and AD are good for autoing, but not for poking, which is Pantheon's bread and butter.
But the real nail in the coffin is that his E is his main damage spell not his autos. Unlike Riven and Talon, he has a cast time. If you are just going to auto for 6 seconds, you are just going to die and not kill anyone. E will do just more damage, and that's the main problem.
We're back to season 2 where there is literally no incentive for Pantheon to upgrade brutalizer. It's a deadend item now for him. You're better off just buying Pick+longsword to build into Hydra for more waveclear, but then you don't have health from BC, which DOES make a difference. His laning phase now transitions poorly.
I understand wanting to gut assassins, and that's the kneejerk reaction most people will have to my post, but Pantheon is not like Akali or Kat or even Talon. I'm not going to say he "needs to get in close to deal damage, which is his weakness" or some bullshit like that. He is safe. He has virtually no counterplay outside of surviving his lane and being ranged vs him. Pantheon's main weakness is that he has one gear: forward. Talon can ult to safety, Kat can ward hop like Lee, Akali's W gives her movement speed for Pete's sake, and Zed...is Zed.
Pantheon can assassinate or even dive, but it's REALLY not advised. He can initiate with his ult ONLY after he's gotten Randuin's and a bit of extra health (i.e. BC) else he will simply blow up. Instead, Pantheon is most effectively played as a bouncer for the carry/ies because if someone does dive, he just shreds them with BC stacks and blows them up with E and his carry. You actually itemize specifically for this role when ahead and really only go full AD ham if your carries are not farmed. Pantheon does not really assassinate well unless someone is out of position in a teamfight (similar to Leblanc.) He has a fairly unusual playstyle where he can't aoe poke like Kat, can't poke safely, but needs to poke or have his team poke before he can go in and catch people.
Now, as a bouncer, the BC changes are amazing. 6% more armor shred? AWESOME! More HP to initiate with? AWESOME? More cdr for faster W's and E's? AWESOME! On-hit MS to bodyblock more easily? GREAT! But in order to get to that places Pantheon needs to have a good laning phase. How good is his laning phase with Phage? Well, I can tell you only having 20 AD from two longswords is a huge difference from a brutalizer. This does let melee go toe to toe with Pantheon instead of being nearly as overwhelmed, but now Pantheon can hardly keep up with ranged tops, which are already a problem for anyone who doesn't want to play tank. Pantheon can't really shift mid that well because he lacks waveclear, so perhaps just jungle with him. At least brutalizer builds into warrior.
I don't want to buff Pantheon with something like "bonus AS makes him channel E faster." That would just break him and do really weird things to him and perhaps make Youmou mandatory on him and push out his bouncer role as being good. I'm just contemplating the future of Pantheon.
