Playtested twice yesterday.
First game, there were bunches of terminal $4 including Ironworks, only one $5 and one $6, so Patron was useless.
Second game, $5-cost cards included Horn of plenty, IGG, Inn.
I often used Patron with Altar and Horn of plenty, mainly to gain Gold. It worked pretty well. From time to time, I had no better use than boost basic Treasure cards.
I'm pretty sure a really good player would have spammed Patrons to empty the Patron and IGG piles, thus ending the game.
Good card, liked it.