Aluminum Steel/Iron Twinborn.

[Fullborn IRL]

I think that the excess Identity of Trueself ferrings can augment iron and steel allomancy by allowing the allomancer to focus on an object touched by the iron or steel lines so that they move, or, allow webs of iron/steel lines to appear among multiple metal objects focused on by the allomancer as a barrier for coinshots since they can push with them and an area that pulls apart things since lurchers can pull with them. Like a magnetic force of pulling and pushing.

[Quantus]

That can be done training, so they wouldnt need Identity.  And I think F-Zinc might be a better shortcut since it allows for "Intuitive leaps"

 

Also, there are indications that Aluminum still doesnt itself get invested when used for Feruchemy and Hemalurgy.  In the case of Feruchemcy, WOB confirms that Compounding Aluminum (specifically) doesnt do anything, which implies that Tapping it wouldnt either.  The most logical explanation is that Aluminum dampens Identity (and Powers in Hemalurgy) because of its Cosmere-wide Investiture-Sinking effect, and that Matallic Arts still dont overcome that effect.  

 

Quote

 

Andrew The Great (paraphrased)

What would happen if a person were to burn a metal that was Feruchemically charged using Allomancy?

Brandon Sanderson (paraphrased)

The metal used in Allomancy is like a key or a doorway to the power that Allomancy actually uses. The metal acts as a filter, much as the Aons in Elantris do, to determine what the power actually does. However, if the metal is Feruchemically charged, then it will basically become a super-burst of Feruchemical power with no Allomantic effect. The Feruchemical charge acts as a filter as well as the metal, and changes what the power does. in this case, say you were burning steel, you would just be massively speedy for a second, and wouldn't actually have the ability to push on anything Allomantically. Hope that answered the question. I get the concept, so if you need me to explain it differently, let me know and I'll try. Oh, the other thing I forgot is that this concept only works if it's a metal that you charged yourself. If it's a metal someone else charged, it would just work like regular Allomancy, and the Feruchemical charge would just cease to exist.

Andrew The Great (paraphrased)

If someone aluminum or duralumin burned the Feruchemically charged metals, what would happen?

Brandon Sanderson (paraphrased)

Basically the same thing as above, except with aluminum. Aluminum, they would just go away.

Idaho Falls Signing (June 20, 2009)

 

 

[Mistchemist16]

You can also argue blanking Identity could be useful too. The steel/iron lines are in the chest because it’s the “spiritual center of self”. In fact, I think you could argue even more metals work this way

Questioner

So, if we switch to Scadrial, and I had lined the inside of my hat with aluminum, I'm protecting myself from emotional Allomancy. What if I was able to use emotional Allomancy? Would that block me?

Brandon Sanderson

So, it's going to interfere a little bit. But the issue with that is, a lot of Allomancy is coming from center and going to head. So, you're probably still gonna be okay with the helmet... So, I'm gonna say, you don't want a lot of aluminum around you, but you could probably still make it work.

Oathbringer release party (Nov. 13, 2017)

Soothing and Rioting come from the chest, just like steel lines. I assume time bubbles and copper clouds work the same. 
 

What makes this interesting is that Cognitive perception also affects Spiritial alignment. It’s why you can’t heal injuries you perceive as part of yourself. My theory is that F-Aluminum can blank the connection to your Spirtual side enough that even basic thinking (Cognitive aspect) decides. So if you blank your Indentity while burning steel, just picture yourself across the road and that’s where the magic thinks you are. So you can put external effects wherever you want. Imagine a Twinborn with A-Cadmium who just casually puts slow bubbles anywhere they want. Just don’t try healing them though. That could be tricky

[IlstrawberrySeed]

Would healing them teleport them?