I was curious how many Kingdom cards Prince does work with, considering there are quite a few it either flat out doesn't really help (Durations), can't work on (Potion-cost), or require cost reducers (cards costing more than $4). Here are my numbers, which might be slightly off:

Durations (8 cards)

Potion-cost cards (10 cards)

One-Shots (Embargo, Island, Feast, Treasure Map, Pillage, Prince)

Non-Actions (23 cards)

Cards costing greater than $4 - requires cost reducer (83 cards, including 19 from above categories)

Total Kingdom Cards you can Prince: 206 - 111 = **95 cards you can normally Prince (46% of Kingdom cards)**

There are also some non-Kingdom cards you can Prince:

Necropolis

Ruins (5 cards)

Mercenary (Madman doesn't work)

Prizes (4 cards)

Total: 10 cards

Even though I'm excited to try out Prince, I am slightly disappointed how many cards it just doesn't work with. And this doesn't even include some cards that would almost always be bad cards to Prince (many forced trashers and Ambassador).