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, 21 February 2008
Hi,
the ability of Kaiu Taru says: "Battle: Discard a card: Abilities on a target enemy Personality cannot be used during this battle. Draw a card."
Can i use his ability to discard a card and draw a new one even if he's not opposed by any enemy personality?
Thanks for your time.
Doruk Özaydın (rules official), 28 February 2008
Can i use his ability to discard a card and draw a new one even if he's not opposed by any enemy personality?
No, because all required targets must be targeted and per Required Targeting: "An action’s required targets consist of anything that is targeted by the player taking the action in the action's constraints or effects, unless the targeting is shown to be optional by terms such as “may target,” or “lose 2 Honor or target a Personality you control.”"
Zen Faulkes (rules official), 28 February 2008
http://rules.l5r.com/FAQ#What_are_required_targets.3F