Multiple Lerasium Alloys

[Iorusys]

So it's made very clear that Allomancers can be either Mistborn or Mistings - no inbetween. You either get one power, or you get all of them. However, it's also been stated that burning an alloy of lerasium and a metal makes you into a misting of that metal. So what would happen if you were to burn multiple, different alloys of lerasium - would all the investiture you burn compound and enhance one ability? Would they override each other, "wasting" the lerasium you previously burned? Would they merge and form a new allomantic ability entirely? Or would they have the intended effect and make you a "polymisting" of the metals that were chosen? Or, is it something else entirely?

[Calderis]

The Mistborn or Misting occurance only refers to natural born Allomancy. 

Lerasium is additive, and alterations to the spiritweb made by it are both specific, and cumulative. 

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Questioner (paraphrased)

Could you become a double misting if you took two lerasium/metal alloy beads (I think the example was iron and steel) at the same time?

Brandon Sanderson (paraphrased)

Yes.

Footnote: This contradicts what Brandon has previously established, that there is no canonical way of being able to burn more than one metal without being Mistborn or using Hemalurgy.
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Shardlet

If Vin and Elend hypothetically each blindly ingested equivalently sized beads of lerasium, would Vin be a stronger Mistborn than Elend, or would they be equal?

Brandon Sanderson

Yes, Vin would be stronger. It is additive, not just an overwrite.

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An alteration made to the spiritweb to become a Misting should in effect be the same as spiking the power in, only more efficient and without the need for murder.