Does Low Stance's battle action ("...After this Combat Segment ends, reduce his force to 0.") and Heart of Darkness' trait ("Before this battle's resolution:...") have the same timing window? Meaning, the active player gets to choose which happens first?
Low Stance / Heart of Darkness
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.
Does Low Stance's battle action ("...After this Combat Segment ends, reduce his force to 0.") and Heart of Darkness' trait ("Before this battle's resolution:...") have the same timing window? Meaning, the active player gets to choose which happens first?
No, they do not.
"After" one phase/segment "ends" is a distinct point in time from "before" the next phase/segment "begins", and the former always comes before the latter.