Complete Frog of War idea

So here it comes: For every capital you conquer you get 1 tadpole-point. If the capital has a harbor you get 2.
Once you acquired 10 tadpole-points you are able to buy a Frog of War which spawns in your home county and can only hop to the nearest capital. The Frog of War has to be moved once per turn, otherwise it disappears. Once it has left the home countries capital it can not go back.
A capital which is currently visited by the Frog of War can not be conquered.