Whenever I kill an enemy with the Soul Reaper debuff still on them, the 50% increase in haste I get only lasts 4 seconds.
Tooltip says 10 seconds.
Bug or have they not updated the tool tip.
It has been nerfed but the tooltip has not been updated yet.
They changed it to 5 I guess when they make it a blood/unholy/frost rune instead of death, but forgot to update the tooltip for whatever reason.
Tooltips require client-side fix, while they can update the actual ability in a hotfix IIRC. Its intended to be 5s, anyways.