Extreme concession (incluso si, aun cuando)

To express that an action will happen regardless of obstacles, use phrases of "extreme concession" like incluso si (even if) and aun cuando (even when / even if). The grammatical mood you use depends on whether the obstacle is a known reality or a hypothetical situation.

Acknowledging Reality: Indicative

When the obstacle is a stated fact, an accepted reality, or a highly likely condition, use the indicative mood.

Even if the camel is tired, the caravan advances.
Incluso si el camello está cansado, la caravana avanza.
Even if the merchant pays, the bandit will steal the merchandise.
Incluso si el mercader paga, el bandido robará la mercancía.

Dealing with the Unknown: Subjunctive

When the obstacle is uncertain, purely hypothetical, or hasn't happened yet, use the subjunctive mood.

Even if we are thirsty, we will cross the sand dunes.
Aun cuando estemos sedientos, cruzaremos las dunas de arena.
Even if it is a mirage, the caravan will keep walking.
Aun cuando sea un espejismo, la caravana seguirá caminando.
Even if the bandits are close, the merchant will rest.
Aun cuando los bandidos estén cerca, el mercader descansará.