Ideas that are shtupeed and probably won't be used.
1. There is no way to make ice. Find one.
2. Combining two unlike elements (ex. Fire + Water) has a possiblility of making a corrupted elikiwhatever, which has to be purified by combining it with a elikiwhatever that is pure, or something. I dunno. OR
3. Combining two unlike elikiwhatevers breaks both down into their base elements. (Hydrogen for water, and less commonly, oxygen and whatever fire is made of)