Originally Posted by Llanite
Building penetration is technically a gamble, since MR cannot go below 0. If you only have 30 MR while he's getting both Liary, Abyssal and Void Staff, he's wasting his money which he could spend to grab more AP and thus, dmg.
Actually, stacking penetration is an extremely safe bet right now (it's nothing close to a gamble). If we go back to the Brand example, we'll see that he can ALWAYS stack at least 30 M-pen since every champion has 30 magic resist by default. After that, you can generally stack up to 50 without worrying too much since every champion that's even partially tanky (from Kha'Zix to Singed) has MR they gain per level to pump them up over another 20 MR by level 18. Sure, you'll waste some gold against squishy champions by going up to 50, so if they're the biggest threat we'll want to stack AP first, but usually they'll have so little hp (since they're building damage too) that you'll effectively kill them just as fast. And, even then, on top of all that, there are many squishy champions that have skills which give them temporary magic resist (like Graves or Annie) where 50 M-pen would be incredibly well spent (not wasted in the least).
So, then, the remaining question would be if Brand wants to pick up Void Staff or wants someone on his team grab Abyssal Scepter. Usually that would be too much and we'd just skip those items as far as Brand is concerned (since he's already got the enemy team at or close to 0 most of the time). However, if the enemy team's tank is stacking magic resist, their support has Runic Bulwark, and their squishy champs are buying some damage+MR items, then either Void Staff or Abyssal Scapter would be very well spent (on rare occasions you'll actually want both).
In the case of an AD burst champion like Wukong or Xin Zhao, stacking armor pen will basically never waste gold except in extreme cases. Even Heimerdinger, who basically has the lowest armor in the game, will have over 60 armor by level 18. Sure, stacking Black Cleaver and Last Whisper would usually be dumb (since the former would reduce the effectiveness of the latter), but otherwise you'll never really have more Armor Pen than your enemy has armor.
Originally Posted by Llanite
Mindlessly stacking MR and be able to counter whatever build they do is the one that doesnt feel right.
Was someone arguing that "mindlessly stacking MR" should counter every burst-mage build? If so, I would strongly disagree with that. Such a system would be simplistic and boring.
All I'm pointing out is how incredibly worthless it feels to stack small amounts of armor or magic resist into champion builds. It currently costs a lot and is very inconvenient to itemize in comparison to how effective it is for you. By contrast, penetration is much cheaper and much more convenient in comparison to its effectiveness. I don't see how its extreme to want splash-resistance items to have some
use for you (other than in games where your enemies are clueless).
Let's look at the specifics:
1. Flat Resistances and Flat Penetration cost about the same in terms of shop gold, mastery-points, and rune slots when considered overall.
2. For any starting value, you'll take a lot more damage when you're moved closer to zero resistance than any you'd prevent by moving yourself further from zero. This makes penetration more powerful from the start.
3. Penetration will ALWAYS work on you and ALL of your allies from the start of the game (up to a limit), but a given resistance item will only block damage coming from HALF of your enemies.
4. It's very easy to stack large amounts of damage (from flat AD/AP & penetration) into a single item slot, but its very difficult to stack a lot of resistances into a single item slot.
5. Penetration is a damage stat mixed onto almost-pure damage items. Resistances are defensive stats mixed onto a lot of damage items (particularly for auto-attacking squishies). This implies that it should be at least somewhat effective to slow a damage-stacking build with small amounts of resistances (but, against a burst champion, it's not).
6. Health currently gives you more survivability for the gold against both stacked damage and penetration damage when compared with resistances (and two of the best penetration items actually offer some health).
In light of all that, it's easy to see why it seems like buying a little armor against a Xin Zhao with a Black Cleaver actually set you back more than it helped you. You've actually delayed your ability to do more for your team for a high gold cost while at every step he's gotten usefulness out of his gold. When you buy a little magic resist against a champion like fiddlesticks, you risk wasting even more of your time and gold since you can easily be brought below zero magic resist (where adding resistances actually does nothing).
Essentially, from the start of a game to the very end, buying ANY armor or magic resist on a champion that can't stack a lot of it (or can't tank for that matter) is a HUGE, HUGE gamble. That makes a lot of really neat items in the shop into things we "mindlessly" ignore. Meanwhile, burst champions are "mindlessly" stacking penetration because it's never a gamble. I'm not sure why you'd think that couldn't be changed at least a little.
Now, obviously I'm not saying certain champions or the HP stat is overpowered (if that's what you're worried about). I'm just seeing issues where certain items and builds are limited into boring territory because of how strongly they are countered before they're even purchased. I think a healthier system where those items are a little viable would be more fun. (Either that or they should be removed from the game or changed to give health/shields only.)