Here is the bug in question:
http://report.nostalrius.org/plugins/tracker/?aid=2417
"Description
If the hunter receives FH buff when any of his shots is in the fly time - FH buff will disappear from hunter without any effect, because that shot hasn't been buffed, but it counts like your next attack. In this situation you'll just waste FH without reason."
So if FH is macroed with aimed or multi shot it will never work as there will be an auto shot in flight. (considering we are not clipping auto shots)
Has anyone figured a good way to use furious howl for self buff in raids?
The only way I can see is to manually click it when there is no arrow in flight, which is insane for just + ~5dps...
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Old thread on the mater: (not very helpful) https://forum.nostalrius.org/viewtopic.php?f=38&t=19512