Why Bloodrazor is Bad
Now to give some context to the things I am about to say. Its concept is not a bad one, but it feels like it was hit with the nerf hammer before it even hit the live servers. First off let us compare it to the once glorious Devourer.
Both Gives you Attack Speed but there are 2 key changes made from the Devourer into the Bloodrazor that ruins the item, or more importantly shifts it from a "Get this item if you have attack speed" to "Get this item if your enemy has 3 or more tanks"
Devourer:
On Hit Damage The devourers main source of damage came from its passive which gave you 30 onhit growing up to 60 onhit damage as you killed large monsters and champions,
Passive Damage once you hit 60 you get an extra attack every other attack. Super strong and this item basically defined the jungle meta for a while, so I can understand why it would be nerfed. But is this to fair?
Bloodrazor:
Passive Damage First off you no longer get the extra attack when sated. Which was what would propel weaker early junglers into late game powerhouses. Bloodrazor does not have this mechanic, instead it encourages you to make use of it early on, as it will likely fall off late game.
On Hit Damage On top of which it is doing 3% Maximum Health on hit. This means that if a player has 1000 Health it will do 30 Damage. If they have 2000 Health it will do 60 Damage, and another additional 30 Damage per 1000 Health. What does this mean? Well:
Caitlyn Health Growth = 524-1884 Garen Health Growth = 616-2049
This means that even when dealing with tanks. Unless your opponent is actively building health, your Bloodrazor will not do more damage to champions than Devourer. And remember that this is scaling to level 18. Early game when your opponent has around 1000 health you will easily be doing around 30 damage. Now you might be saying "This sounds alot like the Devourer" and it does. You can say that the chore of farming monsters has been removed, because the damage of your item now passively scales with your opponent. The lower his level, therefore the lower his health, then the lower the damage your Bloodrazor will do. And vice versa. So if it is doing roughly the same damage as Devourer then why does it feel so much worst?
Countered By the Meta One of the things that made Devourer so strong was that it was magic damage. And if you didnt know, champions in League gain passive armor as they level up, similar to them gaining health. But they do not gain passive Magic resist. So as the game goes on a champion will go from roughly 20 armor to 80, while their magic resist will stay at 30 unless they buy MR items. What this means is that in the past your opponent had to actively build against the Devourer in order to reduce its damage, and now they dont have to worry about that as much, as you will passively reduce its damage as you level up.
On top of which, ADC's deal the most damage late game, which is why most tanks are more prone to building Armor than they are to build MR. Now that your going Bloodrazor your enemies tanks are going to say "Oh thanks buddy, I was going to build armor anyways but now I just have 1 additional reason to do it."
Conclusion As you can see, while on paper Bloodrazor does similar damage to Devourer, the fact that it is dealing physical damage instead of magical damage creates an entirely different dynamic. Since armor for the most part is plentiful and easy to come by and is something you will likely be building anyways.
A subtle, underlying, and possibly intentional change this causes is the fact that mages will be a bit stronger. For the most part most Supports are going to be AP and your MID Mages will be AP as well. And since the supports wouldnt be dealing a whole lot of damage, players didnt really have a great reason to build early MR. And early game is where Mages do the most damage and try to snowball out of control.
But with the introduction of Devourer doing Magic Damage, if you were a tank and saw your enemy jungler going for the Devourer, that magic damage on top of the AP Mid and AP support could make a good case for building some early MR. And so Devourers existence indirectly countered Mages and made life easier for the tanks. But with the shift to physical damage tanks will be more inclined to build additional armor and thus this change indirectly buffs mages.
While I personally like the change itself as I think it dealing physical damage is a lot healthier for the game, I think the % Health damage should be increased to 4 or 5, or that Blood razor should come with 15+ Penetration. This would help it survive in a META that indirectly counters it.
but I do agree it should have additional stats like armor pen or AD