We are in a super early beta testing phase right now, and there are still lots of things that need tuning and also bugs that need fixing.
The developers intentions with Crushing Blow is for it to be competitive with stats like Increased Attack Speed, Critical Hit Chance, or Critical Hit Damage, but obviously it will need some tuning if it clearly trumps all of those other stats.
We are of course interested in reading more of your thoughts on Crushing Blow, so please keep posting your feedback on it :-)
Currently, a Crushing Blow hits for 25% health against normal monsters, for 12.5% health against elites, and after the next beta patch has launched, it will hit for 5% health against bosses.
Keeping in mind that Crushing Blow is subject to changes and tuning since it has to compete with other stats (Increased Attack Speed, Critical Hit Chance, and Critical Hit Damage), what are your thoughts on these percentages?