Wikia

Blood of the North
Blood of the North (Passive) Passive Permanently transforms your Blood Runes into Death Runes. Death Runes count as a Blood, Frost, or Unholy Rune.
Usable by
Class	Death knight
Properties
School	Shadow
Talents
Specialization	Frost
Level required	55

Blood of the North is a death knight ability learned at level 55 for death knights with the frost specialization.

Patch changes

Patch 4.1.0 (26-Apr-2011): Now permanently converts both Blood Runes into Death Runes. There is no longer any proc interaction with Blood Strike required to activate Death Runes.
Patch 4.0.6 (8-Feb-2011): Blood of the North is no longer incorrectly increasing Blood Strike damage by 10%.
/ Patch 4.0.1 (12-Oct-2010): Redesigned and moved to Frost tree specialization.
Patch 3.2.0 (04-Aug-2009): Reduced to a 3-point talent. Increases Blood Strike and Frost Strike damage by 3/6/10%. There is now a 33/66/100% chance whenever you hit with Blood Strike or Pestilence that the Blood Rune will become a Death Rune when it activates.
Patch 3.1.0 (14-Apr-2009): Now also increases damage dealt by Frost Strike by 3/6/9/12/15%.