Yes, that was my point. It's clear to me that, according to the rules, Moat would block the text under the line, which causes potentially intolerable tracking problems. The interaction with Lighthouse is even more confusing.
Oops, mistook your post for someone complaining why it shouldn't work. You're right, of course.
This one gets even weirder because of the lower half. You can't "Moat" your own hand because the "Attack" was not played by "another player." If the card says "Attack" on the bottom, it triggers all sorts of weird things. The only real way to do it is make the "Duration" part NOT affect the other players.
What you can actually do, as i said earlier, is to give out
Tokens, as Embargo does. Like:
Siege+ 1$
Every player discards cards until he has 4 cards in hand.
Each player gains a Siege Token, putting it in front of him. Every time a player who has a Siege Token ends his cleanup phase, he discards down to 4 cards and removes all Siege Tokens he has.
---------------------------
At the beginning of your next turn:
+1$ Action - Attack - Duration
Actually Duration is not needed for the attack, and i know it's a bit different than your original card in edge cases (Council Room). But it's after the rules and works.
(Still giving out Tokens for one-time use is not really pretty, but it's as good as it gets.)