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 October 2009
Hamstrung: Reaction: Before the resolution of an action: Choose a Personality. Negate his movement into attacking armies from the action.
Deployed Reinforcements: Terrain. Battle: Before this battle's resolution, if you control any units at the current battlefield, you may target a unit in your home and move it to the current battlefield. Straighten it if it moved.
My opponent (the attacker) plays deployed reinforcements. Can I play hamstrung... A) Immediately, choosing any personality (who may or may not be targeted by my opponent before battle resolution to move in)? If so, would that personality's movement be negated? Hamstrung does not say 'actions effects' so I would imagine this is the case B) When their personality moves in before resolution (which is long after the resolution of Deployed Reinforcements, don't think this is the case)? C) Some time else entirely or not at all?
Zen Faulkes (rules official), 21 October 2009
My opponent (the attacker) plays deployed reinforcements. Can I play hamstrung... A) Immediately, choosing any personality (who may or may not be targeted by my opponent before battle resolution to move in)?
Yes. Not only can you play Hamstrung then, you can only play Hamstrung then.
Deployed Reinforcements only has delayed effects, so the action resolves (trigger for Hamstrung) before any of its effects happen.
A player, 1 August 2010
In regards to viewtopic.php?f=59&t=79721&p=1043487&hilit=+Hamstrung#p1043487 when the resolution of the action that a players takes wherein they announced to play the terrain Deployed Reinforcements, as I understand the rules, the effects of the action put the terrain into play and the terrain later produces its delayed effect. Since the effect of the action is only putting the terrain into play, although you can legally announce hamstrung, even if you target the personality that the controller of Deployed Reinforcements chooses, that personality would still move, correct?
Zen Faulkes (rules official), 1 August 2010
Since the effect of the action is only putting the terrain into play(...)
No. The immediate effect of Deployed Reinforcements is putting the Terrain into play. Targeting, moving, and straightening are still effects of Deployed Reinforcements, even though they are delayed.
[Additional: Slight correction / clarification: The only immediate effect when the Terrain is played is the Terrain entering played, but it is a rulebook effect, not a card effect.]
(T)hat personality would still move, correct?
Incorrect. "Negate his movement... from the action" applies to all effects of the action, not just the immediate ones.