I don't think the issue with gem gens is the invisible income, frankly I love that part, it's like turning off score graphs. And blood hunting doesn't show up on graphs either.
The problem is like stated above more clams more wishing part, which eventually ends up with a nation getting like 1000 free gems per turn.
Heheh, doe clams Are limited in a way, you can only forge 50 gem gens a turn.
Seriously doe, I love clams, but I consider them broken in certain games. I agree they should somehow be limited, which doesn't sound possible to be honest.
The other things that is grossly broken is invading a fort full of immortals, to be specific vampires. That just isn't possible.
It would be interesting if clams had horror mark ability, I wonder how that would affect their production..?