I mean that's a very complex question. Do you mean in just terms of deaths? By a per capita basis many of the Central European countries lost a great deal more proportionally, 25-50% of their entire population, than did any country in WW2. Poland and Lithuania are I believe the highest in the mid to high teens from WW2. Something like 1/3 of all German towns were destroyed by the Swedes alone. On a pure numbers scale though it's not even close. Somewhere around 8 million people died in the whole Thirty Years War, one tenth of the upper estimate of total deaths as a result of WW2, 50-80 million. As far as political and religious outcomes it was pretty devastating, or at least momentous, depending on whose side you were on. It marked a great reduction in Papal power, freed the Dutch Republic, gave rise to the Bourbon dynasty and helped draw an end to feudalism. And that's really just scratching the surface.