Inactives? If implemented, this is THE card to use for attacking ACTIVE players and stealing their ships. Very powerful.
Comments: I think the highest potential should either be 250k (just like it ordinary is) or 500k (twice the ordinary max). Both of these are easy to argue for. A max of 450k seem arbitrary. The cost of making the card should be higher if the max is 500k, obviously.
Also, I think the duration is too long. This will be a powerful card in the right hands (mine!). I believe that 24 hours is more than enough.