To avoid paradoxical VP counting, it would rephrase the card text like this: "At the end of the game, after counting your initial victory points, subtract 1 point from that number per Palace in your deck for every 10 initial victory points (rounded down)."
But how about having Palace's VPs scale down with the numer of victory cards in your deck instead of the initial VPs?
The card then could look like this:
Palace
Cost: $5,
Type: Victory
Text: 12 VPs | This is worth 1 VP less for every other victory card in your deck.
So 1 Palace would be worth 12, 2 would be 22, 3 would be 30, 4 would be 36, 5 would be 40 and 6 would be 42. 7 are also worth 42 and from then on, it's less. Yeah... I lost my initial train of thought here, so I leave this as it is for now^^
What were your thoughts on the "In games using Palace, whenever a player gains a victory card that is not a Palace, trash the top two Palace cards from the supply." part of the card text, I wonder?