How does this work?
Fire Shield is not an area effect spell, but if the swarm touches the recipient it would take fire damage?
And since the Swarm is all made of little creatures would they get burned up before doing damage?
I would say you do fire shield damage before they attack, if they still have hit points left then it gets to damage the creature it attacking. My two cents. lol.
I would say damage happens at the same time, and you apply the damage against the swarm's total hp. It does not neutralize the swarm by saying "it burns them all up" before they can do anything.