Spell damage? So, like momentum, is not stopped by shields? Also, if it is a weapon (aka weapon slot) it should say "Weapon:" in the front of the text.
Nice idea, but seems to be too similar to Fahrenheit for my liking... stacking damage based on something else. This would also make a life rush even more susceptible to CC, their damage scales with creatures already and now the alternate way to do damage does as well.