How can we improve the existing moving creatures of Minecraft? What are we missing? Please explain what your "new mob" is designed to do, and why it is needed. We are interested in ideas that are unique!

Ice slimes would be a cool addition to the ice biome. There already are types of slimes in minecraft but there needs to be more types of slimes like the ice slime. They would have white icicles hanging down into their eyes and they would be blueish clear. They would inflict freezing effect which freezes the entity, they would have 20 hp and drop frozen slimeballs. The ice slimeballs would be used in a brewing stand to brew a freezing potion.