Well I dont know if this works 100% but I'll put this up anyways.
Well I was in AV today and I'm a low lvl in it. I saw a high level mage and I did one of my tricks I love most. (sap)
I was sapping him for like 3mins and one of the times I sap the mage he used frost nova, I see that he iced me and I sap him without comeing out of stealth and i had no calldown timer on my sap.
By the looks of this you have to do it the same time as the mage dose frost nova so I dont know how good this could be, but what the hell I thought someone might like it.
P.S I Do not have improved sap.