The Zergling Swarm by TwistedHero

The Zergling Swarm, as a unit, generally ignores collisions with heroes, and they with it. Individual Zerglings seem to flow around heroes, though they are not capable of body blocking or being body blocked. Each Zergling is very small, the group of 10-20 taking the same amount of space as a hero like Azmodan when all grouped together.

Each Zergling does very small amounts of damage with each attack, but when completely surrounding a hero will dish out damage about equivalent to Raynor's auto-attack. Each Zergling attacks relatively slowly, but they do not all attack at the same moment, giving the feeling of a constant life drain for as long as one is surrounded.

Zerglings have very low life, but health regen slightly less than Murky. When two Zerglings are killed a Larva will be spawned at the location that the second Zergling died. If the Larva is not killed, two Zerglings will be spawned five seconds later. The Larva take reduced damage from all sources (as is the case in SC2). If the Larva is killed it will respawn back at the Nexus. Zerglings spawned from the Nexus will attempt to rejoin the main Swarm, and will be invulnerable until they do. If the entire swarm is killed simultaneously (by AOE or by exploding as Banelings), 10 Larvae will be spawned back at the Nexus five seconds short of the usual death timer.