T3 Heavy Assault Bots and T3 Siege Assault Bots fulfill the same role - that of a main-line assault bot. Put simply, the continuation of direct fire units from T1 and T2 (tanks etc). They typically have high health, may possess a personal shield, and have good DPS. Their speed tends to be average. They all have reasonable rate of fire, meaning that their damage scales well, from T1 right up to T3.