An idea for Forge & custom games: Turrets. Not automatic. These are placed with a 2X2 flat block with a circular groove in the middle with a magnet which only works with the turrets. The turrets clip on to these with either magnets on or off. The turrets include:
Scorpian - from the tank
Grizzly - From the halo wars tank
Flak - Quad autocannon
Twin Gauss
Twin Machine gun
Missile launcher
These turrets have a cockpit like the mantis with a hatch on the top as usual and have the rotation speed of a shade.