Defiler (StarCraft)

The defiler is a high-tier zerg ground-based "spellcaster".

Strategy
The defiler is a late game unit. It has no direct attack and is slower than other zerg ground units; it is a support/harassment unit. Using multiple defilers makes it easier to manage the simultaneous deployment of Dark Swarm and Plague.

Dark Swarm
Dark Swarm casts a cloud over an area which prevents units under the cloud from taking damage from ranged attacks. Units under the cloud may still be damaged from splash effects. Lurker and firebat attacks are not affected by the cloud. Units outside the cloud may still be hit from ranged attacks originating from inside the cloud.

Dark Swarm may be used to cover the advance and attack of melee attackers, or shelter ranged attackers from return ranged fire.

Plague
Plague has a smaller area-of-effect than Dark Swarm. It inflicts up to 295 damage, to a minimum of 1, over time to each affect unit. Plague affects units and structures. Plague does not affect shields; damage is applied directly to the hit points underneath.

Defensive lines and other enemy concentrations may be softened up with Plague prior to an assault.

Consume
Consume kills a zerg ground unit and restores 50 energy to the defiler. The ability should be targeted on cheap units, like zerglings.

Burrow
As a support unit, burrowing keeps the defiler out of harms way while its energy recharges. It may be used to set up ambushes using Plague, or help preposition the defiler to cover the arrival of friendly forces with Dark Swarm.

Counters
Defilers are an unarmed caster unit, so they are vulnerable to any attacking unit, especially faster air units that it would not be able to run from very well. Specific hunter units are particularly deadly such as vultures and their spider mines and groups of wraiths.

Defilers can use burrow to help hide them from these vulnerabilities.