This is certainly an absurdly long thread.
To elaborate on what atul said, Arcane Nexus is so powerful that, if you have enough players in the game, even if it is dispelled the turn it goes up you can easily make a profit off of it and cast it again. Basically it scales in power with number and strength of opposing players. It's one of the closest things the game has to an "I win" button.
Utterdark makes it almost impossible for most nations to effectively fight. While it's not only are most units not able to hit the broad side of a barn, you also probably can't recruit anything due to the massive income loss.
Gem generators, even aside from being unfun, are micromanagement hell. You have to have hundreds of commanders running around with gem gen items on them, and in the case of fever fetishes they'll eventually die. So you need to pass the fetishes off before that happens. Which means you need more than a constant rate of commander growth, eventually it will balloon preposterously. Gem generators are also too much of a strategy in and of themselves. If you just make enough more of them than anyone else, eventually your gem income will be so high that no one can affect you and your territories are more or less meaningless. Ask micah
