Learn Spanish (Latin America): Vamos a romper la barrera, cueste lo que cueste. - We are going to break the barrier, whatever it costs.

It uses the present subjunctive of the verb costar twice, linked by lo que (what / that which). This pattern is called a reduplicative subjunctive clause, and it is used to express indifference to the exact circumstances, translating to 'no matter what' or 'whatever it costs'.

Why do we need the subjunctive cueste instead of the indicative cuesta here?

We use the subjunctive because the exact cost or effort required is unknown or hypothetical. The reduplicative structure inherently points to an uncertain outcome, so using the factual indicative cuesta would be incorrect in this context.

I remember costar has an 'o', so why is the stem spelled cueste here?

Costar is a stem-changing verb where the 'o' changes to 'ue' when the syllable is stressed. As a quick refresher, this stem change applies to the present subjunctive forms just like it does in the present indicative, giving us cueste rather than 'coste'.

Can I use this same repetitive structure with other verbs?

Absolutely! This is a very common formula in Spanish. You can swap in other verbs using the pattern '[verb] + lo que + [verb]' in the subjunctive to create similar phrases, such as pase lo que pase (whatever happens) or sea lo que sea (whatever it may be).