Mace is a plasma bot that can deal a sizeable damage with relatively low cost of building. It has a shorter range than rocket bots, but if you manage to reach them, it can easily eliminate them. It has slightly higher HP than rocket bots, hence it can be used in big numbers to destroy T1 defensive structures. Combine with resurrection bots, for healing and resurrecting fallen units, to quickly push the front-line. 

Effective for defending mountain tops, as their range is longer when shooting downhill. Always try to get higher ground.

Watch out for Heavy Laser Turrets!