Particle Swarm is the ability to fire a stream of burning orange and black particles from the hands in order to inflict pain on and eventually incinerate a victim. The particles swarm around the victim for a considerable amount of time before it finally vanquishes them, making the victim suffer before they are killed. The only known user of this power is the demon Zankou.
Shortly after he was freed from his prison to help fight the Avatars, Zankou sought out Kyra in the manor attic in the shape of Phoebe Halliwell. As a punishment for her betrayal by siding with good, Zankou revealed himself and unleashed a swarm of particles that severely hurt and eventually vanquished Kyra.