How do you get the seceret medals in primary

Seceret Medal 1 (FrozenFire): Destroy an ice block with Red's fire. You can't do this until level 18 because before level 18, when you change to red, the ice block will shatter and you can't burn it.

Seceret Medal 2 (Ice Cream Headache): Kill an enemy with an ice block. You can't do this until level 6 (there are no enemies yet).