In use by 2505, the ravager is the result of years of twisting and fine-tuning the genome of the roach far beyond its biological limitations. Ravagers stand two to four times as tall as a terran wearing CMC armor, and hardened bone spikes portrude from their backs. Their eyes grant them a broad spectrum of vision. Generating ravagers require dark, humid conditions.
The ravager wields plasma fire both in close-quarters combat and as a wedge to crack open entrenched positions, something the Swarm has struggled with in the past. As an evolution of the roach, the ravager developed a larger, heavier frame to store quantities of fiery fluid in its back. The ravager can launch a gob of corrosive bile from its back in a parabolic arc. This projectile is slow, best used against stationary targets, but can destroy protossforce fields, and is effective against heavy units and structures. The Dominion has theorized that this ability was developed to boost the ravager's utility in assaulting entrenched positions. This mortar-like ability is slow moving however, and ground forces can move out of the way in time.
Occasionally the ravager's exoskeleton would calcify, allowing for more durable armor. Abathur considered the resulting intimidation factor of such armor to be an added bonus. Leviathan Brood ravagers have an even more monstrous appearance than standard ravagers, with spikes jutting out from their bodies (as is normal within the brood).
The primal zerg have adapted a species of ravager known for being brutal and bloodthirsty, known for eating their own young should they not be strong enough to fight back. This nature has put the survival of their strain into question.
Ravagers enslaved by the Cerberus Program were enhanced with plasma spines that superheated the corrosive bile as it was launched.
Ravagers do more damage than roaches. However, their effectiveness heavily relies on player micro due to their corrosive bile ability. Ravagers corrosive bile hits from a long range, and impacts units in a small area around the target a few seconds after launching. Bile will hit both ground and air units in the target area. Corrosive bile also destroys the Force Fields of the sentry.
Ravagers are effective against key units that are otherwise difficult for the Zerg to deal with such as siege tanks, liberators, and deployed warp prisms. However they are relatively cost inefficient and can be dealt with using immortals or marauders with proper micromanagement to avoid corrosive bile. Ravagers have no Light or Armored attribute tag, and thus do not take bonus damage for their armor type, but still do best with zerglings and roaches in front to absorb enemy damage while they dish it out.
Abathur is able to mutate his roaches into ravagers in Co-op Missions. Additional upgrades for them unlock at the roach warren once Abathur reaches Level 4. Biomass decreases the cooldown of the ravager's corrosive bile ability, 0.5% per biomass collected up to 50% at 100 biomass.
Ravagers gain +3% hit points, +1% attack speed, +0.5% Corrosive Bile cooldown and +1% Biotic Leech per stack of Biomass. Can stack up to 100 Biomass. Passive: Heal 1% hit points per Biomass.
Essence Hoarder: Ravagers can collect an additional 25 Biomass (summary 125).
The Limitless: Ravagers can collect an additional 100 Biomass (summary 200), but gain +1.5% hit points, +0.5% attack speed, +0.25% Corrosive Bile cooldown and +0.5% Biotic Leech per stack.
The amount of collected biomass vary, based on difficulty and the amount of supply consumed by the killed enemy unit:
Collect 5 biomass per supply (Casual and Normal)
Collect 4 biomass per supply (Hard)
Collect 2.5 biomass per supply (Brutal)