Awww those pesky Void ults, huh?
I recently played as Xal vs VP Zeratul. When I started channeling my Void Eruption, Zeratul casted VP on me.
Not only my Void Eruption continued to deal damage, but I was also able to rotate my Xal inside VP, along with almost fully channeled orb. VE is not being launched while Xal is inside VP, effectively prolonging it’s usage as melee-range AoE ult. It launches correctly when VP expires.
I melted nearby enemy Anduin from full HP to none, because he was in range of VE with the duration extended by the bug. Currently VP turns Xal that channels VE into invulnerable, stationary turret holding stupendously strong AoE ability.
Well, thank you Zera, was fun but this is definitely a bug and needs fixing.
Edit: Found a showcase of the issue on Reddit: https://www.reddit.com/r/heroesofthestorm/comments/1wu44mw/xalatath_ult_is_not_stopped_by_void_prison/