Honestly an item that gives a dash is probably a good idea
Right now there are a collection of champions who are completely reliant on flash, Annie and Galio being the best examples. Giving them access to a less powerful dash with higher uptime allows those champions to be balanced in a more flat way, instead of the situation you see now where they're absurd with flash and kind of underwhelming without it.
The problem I could see is if the item is strong enough that everyone can get it. Giving immobile champions an escape isn't really what you want this to do, and giving mobile champions more mobility isn't either.
What about some blink dagger style clause on it where it can't be used if you've taken more than x damage in the last y seconds, and/or can't be used for x seconds after another dash or blink?
