APCs:
Some stages have pre-designated APCs within the map. Though non-mobile, they can shed out a great deal of help - trimming down the size of the zombie wave. They are relatively maintenance-free, low-cost, and are also not attacked by the Zombies which makes them quite reliable throughout the stage.
APC Cannon
(Passive upgrade to learn using APCs on field)
Learn to operate cannons on armored transporters.
Damage +30%
(APC passive Upgrade)
APC cannons damage increased by 30%
Damage +70%
(APC passive Upgrade)
APC cannons damage increased by 70%
Speed + 30%
(APC passive Upgrade)
APC cannons rotation speed increased by 30%
Cost -10%
(APC passive Upgrade)
APC cannons activation cost reduced by 10%
Cost -25%
(APC passive Upgrade)
APC cannons activation cost reduced by 25%