With the Brutalizer taken out of the Black Cleaver (that's its own set of reasons), the item can be built into Youmuu's, or into Youmuu's, or Youmuu's.
I think this is against the Game's philosophy of choices, diversity, etc.. You are essentially on a permanent build path. Never at any point can you take the item in a different direction.
Either just get rid of it and re-do the Youmuu's build, or add an item for it to build into.
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Steals flat armor from the target when dealing physical damage.
Though in all honesty, splitting Brutalizer into two items (one that gives AD and CDR and another that gives AD and armor pen) would help a ton with itemization options. AD, armor pen, and CDR all in one package can be hard to build items around without getting overbearing.
build path too limited, come at me OP
If you want to get technical Brutilizer does build into Warrior. Of coarse that only applies if your Jungling.
It seems like riot does not do a lot with the in between items. to say Bruitalizer is too limited in it's build options is not exactly exclusive to that item.
Take haunting guise for example. The Mpen is real good except that it only builds into Liliandry's torment. which most mages don't benefit enough from.
But I digress, Riot probably intends for certain items to have limited build options. It probably works better for item balance if riot only uses the component items where they make sense to balance the final product. And the Final product is ultimately what everyone will strive for. If your can think of a good Final item, which building Bruitalizer makes sense in it's build path, let me know.
Well, we are in need of a new AD+Armor item after they deleted Atma's Impaler.
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+30 Attack Damage
+10% Cooldown Reduction
+10 Armor Penetration
+50 Armor
And maybe a unique passive similar to 
An AD plus armor item is needed in the game right now, which is unrelated to brutalizer building into just one thing. But building it off it is a good idea. Maybe something like
Brutalizer + Chain Vest + 413 gold = Spiked Buckler 25 AD 10% CD reduction 10 armor pen 60 armor Shared passive with tabi's. UNIQUE Passive: Blocks 10% of the damage from basic attacks.
So it has a niche in not being a very strong offensive item for the cost but a good armor item with some offensive stats for bruisers or any offensive ADs who are getting blow up too fast by AD damage. It would be more the sort of item you build to counter something (like a double adc team) on offensive ADs, as opposed to something you always build.
The tabi passive would allow people to get that passive while building other boots like threads and mob, which would be a really nice option to have.
Funny thing is that they hold back the Abysall rework cause the reworked Abyssal fills a different niche and thus they don't change it till they have proper item to fill the current abysal niche.
However, new BC fills a different nich than old BC aswell, and the absence of the old BC leaves a huge gap for ad-caster itemization, yet apperantly no one cared about getting a new item to fill that nich befor pushing through the BC changes.
I think working brutalizer into Essence Reaver would be great, ER still is a rarly seen item that is a bit lacking. By giving it flat pane and therefor lowering the ad, it would be pushed even more towards ad-casters.
Garen 
and Renekton 
weep in a corner because of the early game change to not having access to black cleaver 
through building Brutalizer
PLEASE, make essence reaver build from this item.
Why not make it build into Last Whisper? 35% armor penetration is literally better than 10 AT ALL TIMES (unless it is before Level 3-5, but who has Last Whisper then?)
