Uh, having Dualcast reduce the cast time of Verraise wouldn't exactly be a nerf to Verraise since it would still consistently have a cast-time below the GCD. In fact, since Dualcast presently works by doing a check if the last spell was instant or not (partly to mitigate the effects of chaining Swiftcast I imagine), the fact that Verraise would still have a cast time would actually allow it to proc multiple Dualcast in a row, which could be seen as sidegrade at worst or even a small buff.