After the tourny, I thought the same of this. While it is pretty readily counterable, it has become overused, and pretty strong against bosses. I have already changed it in a way that I think will be a nice change, and I may alter again in the future if the results arent desired.
As many people have noticed, this does not LOWER your spell reduction, but SETS your spell reduction to a negative value. This is what makes it so strong; HP and AMS is the only good counter.
What did I do then?
I made it an aura again! Thats right, it is a passive aura again. However, it is only 15+5% spell reduction per level. This means that passive heroes using MEA, pulverize, static shock, or other units using DoTs, or a slow cast hero with a lot of abilities.. yadda yadda yadda.... The spell damage reduction will not be nearly as strong, but it will be usable on more builds. People using it with a single target nuke will be saddened, while people attempting more unique builds with it will be happy.