How to calculate Blizzard damage

I would like to understand the exact calculation for Blizzard damage versus Wolf / Skull Towers.  I have max and perked Blizzard and it can 1 shot Max Wolf and Level 8 Skulls,  but I want to understand how to make the calculation as damage vs HP of Skulls / Wolf.                                                                                          This is to decide HOW far I should take the perking of damage on Blizz before switching to range.