The reaver can now be set to auto-build scarabs and does not require minerals to build them. It is a slow unit compared to other units, but is stronger and moves quite faster than in the original StarCraft. Due to the general improved AI of StarCraft II, reavers choose their shots better and their scarabs have better pathing and can scale cliffs, making them overall more effective.
Reavers are useful against clusters of enemy units that it can decimate with scarab shots. However, it lacks the cliffwalking of the colossus and wrathwalker, making it more difficult to position, and it moves and attacks slightly slower than the colossus. Compared to the colossus and the wrathwalker, the reaver fills a compromise between the colossus' splash damage and the wrathwalker's higher single-hit damage. Reavers, unlike colossi and wrathwalkers, cannot be hit by anti air.
Artanis can build reavers in Co-op Missions once he reaches Level 5. They can be upgraded once he reaches Level 9. Reavers can be utilized by Amon's forces in some co-op missions.