Summon Swarm Spell
D&D Description of the Summon Swarm Spell : You summon a swarm of bats, rats, or spiders (your choice), which attacks all other creatures within its area. (You may summon the swarm so that it shares the area of other creatures.) If no living creatures are within its area, the swarm attacks or pursues the nearest creature as best it can. The caster has no control over its target or direction of travel.
Deeper info on this Dungeons & Dragons Summon Swarm Spell
Note: Add a Reply about how you have applied the use of the Summon Swarm spell in a previous Dungeons & Dragons scenario.