Bump.

Power bump.

Katarina would not greatly benefit from this item. All of her skills deal magic damage, even the ones that scale with AD. Probably others on your list too.

tl;dr.

also there's only like three guys who would care anyway. two of which do better by specializing and the third of which is Jax.

Yep, Jax, Poppy, Akali, Kayle, Kog'Maw, etc. don't do damage late game.
Best thread ever.

Bump.

The stats would have to be low. Dual penetration is inherently overpowered to begin with, since it somewhat lacks counterplay in terms of what to build defensively.

Think back to the problems with Irelia. She does everything. Magic damage, physical damage and true damage. One of her weaknesses is that she can't effectively itemise penetration to amplify her damage. If she had access to this new item, I could see her becoming a problem again.

Downvoted by someone who knows I'm right. Fact is, if we haven't had a single dual pen item yet, then it quite clearly has massive implications on balance, and Riot knows this. Hell, look at what happened to Kayle and her passive.

Bump.

I gotta agree with Clamface and most of the opposition here.

The true strength of a Hybrid character is in the fact he makes use of two sources of damage readily, making it hard in the first place to get proper counter-play from him.

Another point is, Hybrid isn't technically a supported character type from Riot's point of view. Besides Gunblade and perhaps Rageblade, there are no real items that would sustain a "pure" Hybrid character, they always lean torwards one spectrum of damage, Magic or Physical. Heck, most of the "Hybrid" characters you listed only benefit from Magic Pen, despite them being able to stack AD for their skills, I think Jax would be the only real exception.

If a dual penetration item was to be implemented into the game, it would have to have nerfed stats from that of LW and Void Staff.

Why? Because first of all, it's going to be giving AP and AD. You can't have such an item otherwise, unless it gave some sort of hodgepodge stats like Nashors or Tiamat does. On top of that, you're requesting it give 35% Armor and Magic Penetration. This just screams abuse for anyone with dual stat stacking, yet relies on one type of source damage. Urgot for example, would pick this item up before a Last Whisper. Why? Because the AP would boost his shield, he'll still be getting some AD from the trade.

Secondly, what would be the counter-play of such an item? You're already behind when it comes to building resists, because you have to stack both just to counter that one Hybrid character, and stacking health does no good, because Hybrid characters tend to do a lot of damage.

So the curse of the existence of such an item would have to be either:

1) It's so weak that the characters it was intended for would get more bang for their buck building Void or LW.

2) It's so strong, it'll face abuse from any champion who has AD and AP stacking, or any Champion who has Magic and Physical Damage, while the Hybrid champions it was intended for get decent use of it at best. Heck, even some Mages would pick it up just for the Pen on their AAs.