What is actually Nova?

Nova for tickling and 60 Mana cost for each cast at 40s points.

I guess Nova exists for synergy on Chain Lightning & Lightning build as Lightning Sorc.

What do you guys think about this skill?

i think you can use nova just fine in early (normal) to slow down and disrupt opponents.
and of course as a synergy.
For much more the skill is not to use I think.
But there are many skills that are only good in “normal” and later used as a synergy. I think that it is so intentional.