With Court of Ambition, you punish your opponents by forcing them to lose three life unless they discard a card at the start of your upkeep
You could easily play this as the only Un- card in your entire deck
The rebacked and old proxy cards can easily be identified by their weight and thickness while the blue core proxies are of very high quality and are a bit hard to identify and need to be tested by looking at the details of their printing pattern and direct exposure to light for penetrability
You can't physically mess with another player's hat (or other possessions or self or anything)
So when I look at Prosper, Tome-Bound, what I see is a perfectly functional commander in my favorite color combination, with my favorite D&D class attached to it, and mechanics that actually feel very in-line with warlocks
1 Rograkh, Son of Rohgahh