User blog comment:RealPixel/Eurya, The Claw of the Grave/@comment-26435768-20150609070445/@comment-26459955-20150609104404

I think I've Addressed how hard it is to actually block something successfully. I gave the ability a cast time/animation time so that in order to block an average AA you would need to time your Q in a 0.04 second window. This sounds fair to me, since it's so hard, but some others have said that it's still too op. It's kinda like trying to time a yasuo Q to block an AA.

- The Math is in a post here somewhere, you can take a look at it if you want.