If the swarm jumps, the duration timer is reset to 10s.
Every new creature the swarm jumps to has a chance to resist the spell, thus ending it.
In Origins, this is the only mage spell capable of dealing nature damage - Stonefist and Walking Bomb state in-game that they deal Nature damage, but in reality deal Physical (Stonefist) or Spirit (Bomb) damage. In Awakening, the Keeper specialization allows for more Nature spells.
Using the examples described in Staves (Origins), and Blood Mage (Origins) the damage of the spell can be increased significantly (270+ damage) even versus nature resistant foes lacking true immunity.