A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
Fortress of the Forgotten
Battle: If any enemy units are at the current battlefield: Target a non-Unique Personality face up in one of your provinces. Bring him into play at the current battlefield. If he is a Berserker, you may ignore his Gold cost; if you do and he entered play, destroy him before this turn ends.
I use the Fortress' action to bring a berserker into play at the current battlefield, and i choose not to ignore his gold cost. I don't destroy him before this turn ends, right?
Fortress of the Forgotten: I use the Fortress' action to bring a berserker into play at the current battlefield, and i choose not to ignore his gold cost. I don't destroy him before this turn ends, right?
Correct.