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.
A player, 15 October 2007
Relevant Text:
The Khan's Gambit Winter Terrain Battle: Your Personalities have +1F and cannot move home. You cannot use abilities on your cards at this battlefield.
Determination Dark Virtue Reaction: Before you announce an action, target one of your Samurai: The action can not have its effects negated or have its targeting changed. After the action destroys any Personality, remove him from the game.
If I played The Khan's Gambit, can I use an ability on one of my personalities if I react with Determination?
Zen Faulkes (rules official), 15 October 2007
If I played The Khan's Gambit, can I use an ability on one of my personalities if I react with Determination?
http://rules.l5r.com/Glossary_C#Cannot: "In card text, when referring to entering play, attaching, using a trait, or taking an action, 'cannot' and 'can only' are restrictions on the legality of that thing in the first place, not negation of its effects." No.