I do like this idea of moving while casting for like 1 time if of course it had a trade off. I think at the top of our heads we can't determine the correct trade off and would have to see how it would effect players to see if the trade off is worth it and bearing in made we can give it a few trade offs.

1. More MP cost,
2. Longer Cast time
3. Less damage
4. None of the above but a long CD time.