So this WoB says that it is possible to soulcast metalminds.
Questioner
Can you Soulcast an Invested object?
Brandon Sanderson
Yes, but it's much harder. But humans are Invested, and you can soulcast humans.
Questioner
So, suppose you had a goldmind that was filled. And you tried to Soulcast into iron. What would happen to the Investiture inside it?
Brandon Sanderson
So, the Investiture would remain in there, but it's keyed to the wrong thing, so you wouldn't be able to get it. It'd be much harder to Soulcast that, by the way. The more Invested, the harder it is. But Soulcasters are used to it, because everything has Investiture, and most of what they're Soulcasting. They deal with this, so it's something they're kind of expert at. So, this is not outside reason, that it could happen. You could give it to your average Soulcaster on Roshar, and they could make it happen. You just wouldn't be able to get the Investiture out of it anymore.
So, in a little debate in the RoW spoiler thread, this was brought up (Don't worry, no spoilers here. These are all hypotheticals) about the TLR and how to beat him and that they said they could just soulcast his metalminds, using this WoB as evidence.
I say that this means it's possible, it's not easy and that TLR metalminds would be filled to the brim and then incredibly difficult to soulcast. The WoB even confirms this. " It'd be much harder to Soulcast that, by the way. The more Invested, the harder it is." SO it follows the same rules for pushing on mtelaminds, where it's possible, but it gets harder to the point of impossibility. he counters that a herald during the time of honor with the massive amounts of stormlight that can soulcast, like Battar, would be able to push through. I say that might be possible but still extremely difficult.
What do you all think of that? Do you agree that the TLR bands -which are likely filled to the brim- would be nearly impossible for any normal soulcaster to cast? And what about a full-powered Battar?