Kalran: Tales of the four nations/Foundry

Support foundry
Simply put. The support foundry is built to create auxiliary defenses, which are to support the proper turrets, and is the cheapest of the three.

Defence foundry
The defence foundry focus on building up the BGF basic turrets. Which are cheaper and quicker to build than the advance foundry. But its intended role is to act as a supporting defenses to the advance turrets. And therefore will fall against a spirited assault.

Advance foundry
The advance foundry holds the BGF heavy turrets, which has the power to wipe out an army and incredibly long range. But it takes up a large amount of space, power intensive, and locked in one direction means a smart commander can either send their forces in waves, utilizing the tower low rate of fire, or flank it.

Mobile foundry
The mobile foundry is responsible for building mobile turrets. Which can move and set up elsewhere and don't need a power field to function. But this comes at the cost of being weaker then other turrets, since its role is to be a stopgap defence to hold territory until the commander can set up a proper defence. And once it sets up it can't turn back but it can be salvaged, refunding it's cost proportional to its remaining health.