Request for balancing for Mark of Blood

I don't like asking for nerfs for other classes, especially before season 5 starts, but this ability really needs a change to balance it so that it affects all classes equallly.

Mark of Blood
1 Blood 30 yd range
Instant 3 min cooldown
Place a Mark of Blood 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.

Please just change it so that it can only proc once per second. This may apply to my class then to others but isn't it just a little ridiculous that this ability could cause me to heal a target for 20% of their life in a single second.

If this is applied as I stormstrike a target that's 2 attacks, the white melee attack makes 3 and if it procs a windfury that's 2 more attacks, so that would be 20% of the target's maximum health before I even had a chance to notice that it was applied.

Certain classes are designed to attack more frequently then others but for much less damage and this ability unfairly affects those classes a lot more, creating an imbalance in the power of the ability and that is the imbalance that adding the change to only allowing one proc per second would correct.