Proceate is similar to Greenstuff, in that they are both epoxy putties. Procreate does have somewhat different properties, however. Procreate is much less sticky than Greenstuff, and when dry has a surface that feels more like plastic and less like hard rubber (depending on how you mix your Greenstuff and what additives you may use).
You could certainly use Procreate to make a water/ice effect (depending on how you want to paint the finished sculpt), but it sounds to me like you might prefer one of the scenic products that mimic water and/or ice instead.