Cantrips that creates these areas could do so when cast on the ground, therefore foregoing the damage for the effect. I think tjat woulf be a good change. And wouldnt create unexpected situations like burning a web spell.
Adding saving throws to these areas is great as well.
C'mon guys. We already paid for the game. Let's help make it better.
At the very least, I think that
- Targeting a creature does damage and does NOT create a surface.
- Targeting a surface which a creature is standing on creates a surface, but does NOT do damage to the creature.
- The creature, upon starting their turn on a surface, gets to make a DEX save (based on the caster's spell DC) to see if the surface affects them.
- Surfaces or effects tick exactly once and then expire, because it's a CANTRIP.
It's the deals damage AND makes a surface AND they don't have a save part which is far too strong. Especially for things which last for more than one tick.