Rework Flash
Since flash is not an option on 99% of champs (it pretty much mandatory)...Maybe it should not be a summoner spell. It should be easy enough to incorporate early in the game. I have been thinking tying it into your tier 1 boots would be the way to go (not sure how to fix that for Cass)
That would also open up alternative flash options. Right now it's what 400 teemos with a 265 second cool down. That's one option, you could have another with a 600 teemo flash and a longer cool down. A 200 teemo flash with a speed burst at the end. Some kind of flash back (think LeBlac's W). Who knows how many options the design team could come up with.
Giving these options on tier 1 boots means you can start with it, if you choose to. Have more out play options. And, you can actually have 2 summoner spells to choose from. I would really like to take teleport and ignite top lane sometimes.
You guys have any other flash options?