From Populous Wiki

Mana Required : 400
Shots : 4
Range : 12
Duration : 15 seconds
Incantation : Wunaga
If you cast this spell on followers of the enemy tribe (it won't affect you or your followers), those followers will spread apart and run away screaming. If you cast it next to a Guard Tower with a shaman in it, she will run out of the tower screaming.

You get this spell by worshipping the Vault of Knowledge in level 2:Night Falls.

It is most useful to disrupting enemy attacks and stopping enemy preachers from converting your men, as well as forcing a group of enemy followers to exit the boat or baloon they are currently manning.

Also, in multiplayer games, swarm will instantly kill ghosts (except shaman ghosts).

Discovery Speech

Spell breakdown

Standard Spells: BurnBlastConvertSwarmInvisibilityMagical ShieldLandbridgeLightningHypnotiseTornadoSwampFlattenEarthquakeErodeFirestormAngel of DeathVolcano
Guest Spells: BloodlustTeleportArmageddon
Multiplayer Spells: Ghost Army
Forge World Spells: FlattenLandbridgeErodeHillValleyRaiseLowerWildmenTrees