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 August 2008
Can a Monk cast Stain Upon the Soul and target himself as the recipient of the bonus (effectively doubling his Force and Chi)? As it is an old card with old wording I can only assume that the Kiho doesn't require two different targets but I'd like to be sure. Thank you!
Kiho Open: Bow any one of your monks or shugenja. Target any one of your monks. The target monk gains force and chi bonuses equal to the force and chi of the caster. Until the end of turn, if the target monk is destroyed, so is the caster.
Brook Cunningham (rules official), 21 August 2008
Can a Monk cast Stain Upon the Soul and target himself as the recipient of the bonus (effectively doubling his Force and Chi)?
Yes. Nothing in the current rules prohibits it.