You have a 15% chance after dodging, parrying or taking direct damage to gain the Scent of Blood effect, causing your next 1/2/3 melee hits to generate 10 runic power.
Patch 6.0.2 (2014-10-14): Level reduced to 55 (was 62) and redesigned. Now activated from [Blood Boil] and [Soul Reaper]. Additionally, using Blood Boil will now refresh your diseases.
Old: Your successful main-hand autoattacks, dodges and parries have a chance to increase the healing and minimum healing done by your next Death Strike within 20 sec by 20%, and to generate 10 Runic Power. This effect stacks up to 5 times.
Patch 5.4.0 (2013-09-10): Now also has a chance to activate when the Death Knight dodges or parries a melee attack.
Patch 5.0.4 (2012-08-28): Redesigned as a level 62 Blood specialization passive ability (was a tier 2 Blood talent). Your successful main-hand autoattacks have a chance to increase the healing and minimum healing done by your next [Death Strike] within 20 sec by 20%, and to generate 10 Runic Power. This effect stacks up to 5 times.
Old: You have a 15% chance after dodging, parrying or taking direct damage to gain the Scent of Blood effect, causing your next 1/2/3 melee hits to generate 10 runic power.
Old: You have a 15% chance after being struck by a ranged or melee hit to gain the Scent of Blood effect, causing your next 1/2/3 melee hits to generate 5 runic power. This effect cannot occur more often than once every 20 sec.
Patch 7.0.3 (2016-07-19): Removed. 
[Blood Boil] and 
[Soul Reaper]. Additionally, using Blood Boil will now refresh your diseases.
[Death Strike] within 20 sec by 20%, and to generate 10 Runic Power. This effect stacks up to 5 times.
