1)The fact that everyone can use disengage whenever they want is just unbalanced. Opportunity attack is just useless if every archer just disengages and shoots you.
2)There are just too many surfaces, why would a cantrip create a surface and why would acid on ground affect ac. I think flammable oil being set on fire by a fire spell that either aims at it or creates an aoe effect is fine, but a fire bolt shouldn't be able to create a surface on some normal stone or soil.
