which bow skill is good at against single target?

except lightning rod.
now I use rain of arrow and spine+barrage to slove map boss.
ROA's dps feels still a little low and it need target to keep standing, spine have good damage but the perfect channel time is hard to do, and it would have spread when barrage it, so it can't deal high damage on long distance or target is not big enough. and channel spine need to keep standing is also a danger.
which other bow skill is good at single target?