User blog comment:JmLyan/Zenbakia, the Number Master/@comment-6061249-20130619183502/@comment-7481207-20130619200638

Final Countdown might seem like a sure kill without drawbacks, but it does have them:

First, it has a low cast range, you can't just ult and recall and expect that noone is gonna do something about it.

And second, if you are going to avoid combat so you cannot die and risk losing the mark on the enemy, then you have to stay away from team fights for at least 80 seconds. More than the time spent dead usually is. So if you use it that way, it is a little bit 1 for 1.