To echo what's already been said:
Cantrips should work as written, but also allow for player creativity.
The cleric cast create water making a puddle of water. Cool. The wizard targets the puddle with ray of frost. NOW it should create the icy surface, but probably no more than a small radius. The game should reward creative intent.
Basically this.
If an enemy is standing on stone, using Fire Bolt on them should not create a fire surface. If they're standing on oil, targeting them should probably ALSO not create the fire surface. But targeting the OIL should create the surface (but no direct damage to them).
