One-on-one, a Scarab will generally win in a fight against its enemies, as it regenerates a good amount of damage per second, often faster than damage can be delivered. A Scarab can heal fast enough to retain approximately 50% of its hit points if hit by a Psi Storm, and over 80% of its hit points after its regeneration has been upgraded.
Scarabs work well in small skirmishes rather than large encounters, because they are vulnerable to focus fire. Scarabs have the ability to spit a poisonous substance a great distance that ignites upon contact with relatively low heat signatures. Although the Scarab is very similar to the Zerg Roach, It lacks the ranged attack of its "cousin".
Scarabs are also vulnerable to sustained damage. Scarabs are strong against opponents that attack slowly and do low damage per attack, such as Protoss Zealots.