Marking this one for replay retention in connection with my Lessons Learned collection, particularly picking Impaler targets.
1) Direct-fire skirmishers like Fencer, when on a hill, need to be positioned either at its military summit or well behind it; otherwise, units can use the hill's vision shadow to avoid taking hits while getting into range.
2) Impaler groups can get sneaky damage, or even kills, idle or working front-line Commanders. Guarding the Commanders wouldn't help.
3) In general, heavy raids should only double back when there's no other reasonable choice. Doubling back makes slow defenders more relevant, and also wastes scouting potential.
4) Impalers are only as good as the team's scouting, and it's well worth sacrificing a Dart to identify potential static targets.