The Pluperfect translates to might have or would have, as in hostis praeventūrus erat, "the enemy would/might have prevented it (Liv. 22.24)".
For Example: He would gain nothing.
audio, audire, audivi, auditus, to hear:
Active Pluperfect: Use the 3rd Principle Part (audivi) and add "-isse" and then personal endings. Audivissem would become "I would have heard".
Passive Pluperfect: Use the 4th Principle Part (Auditus), and add the imperfect tense of sum. So it would become Auditus essem which means "I might have been heard".