"We’ve recently heard reports about a mysterious new weapon in the hands of the Zerg. We’ve heard of battlefields being covered in a dense, blinding cloud, rending our guns all but useless, and of Battlecruisers escaping from battle only to be yanked back into the fray. The source behind these bone-chilling truths is the Viper, and we now have a full intel report on not only what it can do, but how."
The viper combines several vicious biological weapons to weaken enemy forces and give an edge to the Swarm. They are a specialized offensive-support strain, being perfectly evolved for battlefield manipulation, a role previously held by the defiler, which the viper contains genetic material from.
Vipers lack any form of direct attack, but they are extremely dangerous in their role as a support strain.
The viper's tail is largely unchanged from the original defiler template. However, it has been evolved to allow the viper to maintain its balance and direction while flying, as well as steering. What truly stands out, however, are the ingrown, crystalline spikes on the tip's surface. These "crystals" emit a powerful pulse that the viper uses to locate its targets with pinpoint accuracy. Its limbs, while formidable in appearance, are crippled in terms of offensive capability, as the Swarm relegated them to the role of simplistic vice-grips. The protruding spikes are porous bone structures, able to pierce flesh and immobilize prey without inflicting lethal damage, and are directly linked to the creature's lymphatic system. When on the prowl, the spikes exude a pheromone that makes the viper seem innocuous and non-threatening to its hapless victims.
Vipers store a thick microbial soup within their abdomens, and can spray the viscous mixture into the air whenever ranged foes approach, essentially nullifying the effectiveness of their armaments until they can move out of the cloying mist. This mixture is effective against both projectile and energy-based weaponry, and can reduce the zerg's foes to fighting in close quarters.
All vipers possess a prehensile proboscis–an elongated organ that serves as the viper's digestive system, and one that runs the entire length of the creature's body. Just as a frog uses its tongue to catch prey, the viper regurgitates its flexible intestines with great force in order to grab and pull a target towards its location. Enemies hoping to escape to high ground are quickly snatched from their dominant position by the proboscis, allowing the zerg to counter just about any tactical terrain advantage. This muscle is powerful enough to even draw a battlecruiser towards the viper.
When fatigued, the viper can siphon bioelectrical energy and nutrients from friendly zerg buildings, allowing it to quickly return to the fray. This is achieved by separating the ionic chains present in the hardened tissues of Zerg nest structures to produce a nourishing fluid. Said fluid acts as a catalyst for the plethora of microorganisms present in its bloodstream, which generate bioelectrical energy to replenish the viper's stores.
As one of the original zerg broods, vipers of the Leviathan Brood exhibit more defiler tendencies than that rest of the swarm. While this has caused many abnormalities to surface, its potent toxins appear to be worth it.
Viper enslaved by the Cerberus Program were given a hammerhead cranial implant that enhanced the accuracy of their proboscis.
Vipers were originally a type of primal zerg. Their uniquely vicious defenses drew the attention of Abathur, who brought their essence into the Zerg Swarm. With the need for a support strain apparent, the defiler template was revisited, and perfected with genetic material from an unknown species, preserving its core functions, but excising the defiler's lethality, which had been as deadly to zerg as it had been to the Swarm's enemies.Abathur incorporated the viper's gene sequences into the Swarm himself. Later, Sarah Kerrigan was able to evolve her own vipers from the mutalisk strain.
Creates a parasitic cloud on an air unit after a 0.7 second delay, dealing 120 damage over 7 seconds to that unit and any air units around it. Cloud has a radius of 3. Cloud persists for the remaining duration if the target is destroyed. Does not stack with other parasitic bombs.
The viper strain of the mutalisk has the same statistics as a regular mutalisk (but aesthetically, it is different by having four blue wings), but can transform itself into a viper at a specific mineral, vespene and time cost.
Abduct costs 25 energy and lacks a cooldown, Disabling Cloud replaces Blinding Cloud and prevents shooting from beneath the cloud entirely, Consume targets allied units, and the viper can directly attack air units.
Compared to the brood lord, the viper is rather similar to a corsair, an air-to-air fighter with a temporary ground disabling move, but with a weak automatic attack, and the bonus ability of being able to move ground units to itself. But in terms of raw fighting ability, its air-to-air ability is not noticeably better than the baseline mutalisk given the latter's multi-bounce attack.
Abathur is able to mutate vipers in Co-op Missions once he reaches Level 8, and can upgrade them at Level 9. These vipers have an anti-air attack that does 10 damage. Amon's vipers and Abathur's vipers use Disabling Cloud instead of Blinding Cloud.
Vipers gain +3% hit points, +1% attack speed, +5% energy regeneration and +1% Biotic Leech per stack of Biomass. Can stack up to 100 Biomass. Passive: Heal 1% hit points per Biomass.
Essence Hoarder: Vipers can collect an additional 25 Biomass (summary 125).
The Limitless: Vipers can collect an additional 100 Biomass (summary 200), but gain +1.5% hit points, +0.5% attack speed, +2.5% energy regeneration 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)