[Zenzei]

How effective is it?
I'm pondering about using the said spell in MP game and I'd like to know what kind of kill percentage I can reliably expect before I spend 50 water gems into it.

Target army is composed of humans and temperature scale is neutral. Wolven Winter increases the effectiveness but how big is this increase, is it practically mandatory to use WW before using MW?

I don't need any super accurate results but some general thoughts from players that have actually used MW would be nice.