Mark of Blood

Mark of Blood is a death knight talent puts a 20 second debuff on an enemy. Whenever the marked enemy deals damage to a target, that target is healed for 4% of its maximum health. Lasts for 20 sec.

Tips and tactics
Mark of Blood is best used on targets that deal weak damage a lot of times, such as rogues and hunter pets. More commonly referred to by rogues as the "death knight bubble".