Ice, Fire and your enemies
Since all ice attacks cause slow and stuns, all fire attacks should give the enemy a speed boost but apply damage over time.
Cold = reduces vibration of molecules and molecular movement range. A person runs slower in colder temperatures until their body heats up.
Heat = increases vibration of molecules and molecular movement range due to expansion. A person on fire runs like Usain Bolt until the fire is out.
The difference between swimming performance in a pool that's 60 degrees as opposed to 75 degrees is very drastic, as in running/bike riding in 40 degree weather in comparison to 85 degree weather.
All the ice champs seem to have slowing abilities. On the other hand, I think you should get a 5% or 10% movement speed boost when hit with fire abilities by 
but doesn't put those champs at a disadvantage because of burn damage (which would also have to be implemented).
