Make new Wizard spells called Ice Wave and Lightning Wave. It has the same damage/range/cost as Fire Wave. The only difference is the graphics and the property of the spell. They will be ice and lightning respectively. This way wizards have a choice and it makes resist ice less useless.
ice wave graphic:
http://www.swfcabin.com/open/1267442070
lightning wave graphic:
none bc = 7am bed time