Oh, come on, you just have to look out for their buff, root/snare them and after 5 sec, profit
It's not a godmode button, just delaying the unavoidable
And FYI, before the several latency/ability delay "fix", this skill more often than not fired off at like 1% hp if not at all, you had to be dead before having any system message about it lol.
And any bad mara/mousclicker will be dead anyway as they struggle to click this skill.
Or they'll just get stun before being able to use it