I have been doing some playtesting with this idea. The original version caused too much delay while you searched through your deck and discard pile looking for that one Attack card. I decided to try a discard attack that only hits other Attack cards with the following wording. This was better but could still stand improvement.
+$2
Each other player discards an Attack card from their hand or reveals a hand with no attack cards.
You may trash this card. If you do, gain a Victory card costing up to $6. Each other player gains a Victory card costing up to $3.
$4 Action - Attack
It was still kind of weak as an attack. I actually bought it most often to trash for 6 VP Fairgrounds. My wife wants to give it +1 Action and drop the trashing part. Instead I'm thinking of dropping the cost to $3, making you choose between the attack and trashing, and changing the trashing to just gain a Victory card costing up to $5 without giving other players anything.
Any thoughts from the group?