For AD's it gives a bit of Damageand health and Armor Pen.
Why not a bit of symmetry?
Or make it the hunting guide, make it look like an amplifying tome.
League of Legends likes to avoid mirror items that do not fill an important niche.
What Exdeadman said. Also, your suggested item overlaps too much with Brutalizer, which has physical damage, armor penetration, and cooldown reduction, at a similar price point.
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