Interesting.

Definitely not for the Stronghold, as there's no way you can keep high-bidding in the endgame.

Again, I love to see a very simple design that is taking some of the complex elements in the game. This seems cool, although trickier to actually get the most out of.

My first instinct is to write this card off as "high strength province with no repeatable ability".  In general, I think there are several of that type of province and there's really no place for them in the game right now.  My second thought is - what if all your provinces were unbreakable?  Scorpion would probably be the one to do it (maybe Crab?) - keep all the provinces from breaking, gain money, apply dishonor pressure.  You can use Shoju/Kachiko as a finishing move, or 20 Force Yoritomo, or just dishonor dishonor dishonor.

So then, the question of where this province fits in - personally, I think it has to go on the stronghold.  If it's in the provinces, then you're bidding high and hoping they go for it early, and if you CAN'T keep high-bidding in the end game, then it will be a 2 strength piece of garbage by then.  So, best case scenario they hit it once and bounce, then kill it when you bid low.  Even if you CAN keep high-bidding in the end game, your enemy can go around it or farm it endlessly at their leisure.  Still, a Public Forum for Water isn't horrible. 

But on the stronghold, you can vary your bid throughout the game, but you KNOW when a stronghold attack is a possibility, so as long as you're not in honor trouble, you can save your 5 bid for when you need it.

Personally, I think putting this on the stronghold has drawbacks, but putting it anywhere else seems worse.  Still, I want to give it a try, possibly as part of an all "unbreakable" province lineup.  I think that style of deck will eventually be a thing, but needs to have a way to punish non-breaking attacks (other than Pilgrimage and repeatable Action provinces).

Also, fun interaction with Maze of Illusions - your opponent will know you want to bid 5 to get the province up to 10 strength, but also that 2 less province strength is well worth sending a guy home bowed, so... you're obviously bidding 4 or 5, but which one.  (I believe the best hybrid strategy is to bid 5 about 60% of the time, but I haven't done the math, and it probably depends on the force of the guy you target.)

Very good spot that. One of the few ways to set a dial high with no honour cost, that card.