If it does not have rush when it revives it become a bit of usless.

You play it. Then your oponent kills it and not the egg.

When it comes back you can not attack as it got summoned at the begining of the turn....

If it has rush when it comes it can be quite of a good card, or does not have summmonig sickness and can even go face then it can be quite broken in a quick agro elemental mage.