* GameBreaker: Eden's Thor's Hammer. Very powerful, has the longest range of any weapon, and requires no line of sight (it can hit over walls and cliffs). Given the ArtificialStupidity of the enemy sending waves along a given path, a line of turrets behind walls will take care of them to the point where there is no contest. The best Plymouth has in terms of damage is the [=RPG=], although the ESG supposedly can do a good bit of damage.
* HellIsThatNoise: The eerie hissing noise when the Blight infests your structures.
** Also the two most dreaded Savant announcements: "The Blight is approaching!" and "Volcanic eruption detected!" The sharp note of urgency in the computer's normally placid voice doesn't help.