When I cast Heavy Mist on someone, are they able to see what their watchtower allows them to see as well as their allies? Do I have to cast it on more than one target, or just one?

Thanks.

Yes their radars outside of their colony will still allow them to see as well as the radar of their allies near them.

So if you want to blind someone completely, you must cast heavy mist on all of their alliance mates near them as well as radars near the.

-Gaurav