A surprise attack by Erec and his men with their new super weapons leave Kon and crew running for their lives.  In the aftermath, each group is left with a prisoner of war to “interrogate”.
You should know that your 
efforts will be futile.
Deben saber que sus esfuerzos son en vano.
Debéis saber que vuestros esfuerzos serán en vano.
Vocês deveriam saber que
seus esforços são inúteis.