Infiltrator Prison Rescue
The ability for infiltrators to attempt to rescue a captured noble from prison, this would be performed in the capital of the realm that holds them. As with all infiltrator actions, this would be possible against both your own realm and against foreign realms. It would, of course, also carry considerable risk of just landing you in a less than comfortable spot beside the chap you were there to save. If you pull it off perfectly, all would go well, your both free. If you fail horrifically, you'd end up in prison, and if you get somewhere in between then you get away but were spotted, making further attempts harder, similar to other infiltrator actions.
Pros: More uses for Infiltrators that can have meaningful impacts, specifically in high risk high reward situations.
Cons: Potentially hard to code. If Balanced poorly on skill requirements, could be over powered?