How do you believe it is overpowered? Too much penetration, armor, cost, etc.? I would guess that the Black Prince probably got nudged into being a bit too powerful when Relic added the extra +100 armor ability to it a few patches ago. Maybe the Black Prince could have a unit cap of one on the battlefield similar to how the command tanks work? I try not to adjust the weapon stats of units so that they stay in sync with the vanilla game stats. That said, maybe the cost, popcap, and/or armor values could be tuned better.

Well they're pretty un-killable unless you send them into enemy lines by themselves unsupported. They are way too powerful. They can also kill any tank that is put in front of them, especially since the AI don't build Panthers or Tigers... If you could make it only 1 tank that would work. My friend builds like 6-8 at a time and its just, game over at that point... and its not just the Black Prince, all the Churchills have insane armour. I know they did actually have good armour, but since you can just build so many its overkill

The Allied AI only seem to build Matilda IIs and no other heavy tanks (but thats probably for the best, they're strong enough as it is)

So far as I know the AI should be able to build heavy tanks, but I think it always opts not to in favor of spamming M3s and M4s for the Allies and Pz III and IVs for the Axis. I'll look into adding a cap on the medium tanks to perhaps force the AI into building heavy tanks. As for the Black Prince, I'll get a single unit cap on it for the next update. Not sure about the other Churchills though as 6-8 of them in a single game seems like a crazy amount of resources spent. Maybe I'll start at incrementing the popcap a bit which should at least penalize spamming too many of them.

Literally minutes after my last post I played a game and the map had high resources and the AI built some heavies. Not a lot, but some. No Tigers though.

Thanks for looking into solutions!