[Updated] v.142 - Dawnveil: Demons of Tynerum Update Notes

so the attack is the usual 1500 ms delay? meh not much use to it indeed then

It doesn't seem to have much of a delay in this video:
[video=youtube_share;BVY7EnA_iu8]http://youtu.be/BVY7EnA_iu8[/video]
(He uses it at 0:23)

The actual attack animation is obscured by Zakum, but you can see that he uses it and jumps away pretty much instantly while the attack continues, so at the very least it isn't an ultimate that roots you to the spot like Kanna's ultimates.