A simple effect. While allowing red to destroy a subset of creatures and enchantments is a minor bleed, this a flavour win. The ability to destroy snow permanents feels red, hasn't been placed in the colour pie and being cold based gives something to interact with. So long as there are no red/colourless ways to turn something snow, this should be fine. (costed as a modern land destruction spell). -I am aware of http://markrosewater.tumblr.com/post/139648763453/could-red-in-theory-get-destroy-target-snow.