RE: This.
Pardon me, but the original poster was correct.
Shokushu no Oni received errata making his trait into a Reaction.
Thus, the original question remains unanswered.
RE: Shokushu no Oni and Spider's Lair
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.
RE: This.
Pardon me, but the original poster was correct.
Shokushu no Oni received errata making his trait into a Reaction.
Thus, the original question remains unanswered.
Thanks for the catch. Fixing.