It is like this: the damage dealt == income.
Soo...
first you must buy a low level gun to kill the creeps, then when you wanted to Com-hunting you equip your Com with Com killer weapon. (you can instantly change weapon at anytime)
The objective is to destroy enemy's command center. You can do this by making your Com a SUPERMAN (that can kill everything) or you can buy units that overwhelm enemy defences.
The number of Com respawn is unlimited.