Call Plague

You call forth hundreds of ravenous, disease-ridden rats, congregating to form a swarm at a point within range. The swarm uses your spell attack bonus for their attacks, but otherwise have the statistics of a swarm of rats. Any creature that is hit by an attack by the swarm of rats must succeed on a Constitution Saving throw or suffer 3d6 poison damage, and be poisoned for one minute. A creature poisoned in this way may repeat their Constitution saving throw at the end of their turn, ending the effect on a success.

The swarm is friendly to you and your companions for the duration. The Swarm shares your initiative count, and takes its turn immediately after yours. It obeys any verbal commands that you issue to it (no action required by you). If you don't issue any commands to the elemental, it defends itself from hostile creatures but otherwise takes no actions. You may disperse the swarm as an action, ending the spell.

If your concentration is broken, the swarm doesn't disappear. Instead, you lose control of it, and it becomes hostile toward all creatures. The swarm still uses your spell attack bonus and deals poison damage after your concentration is broken. The swarm cannot be dispersed by you while uncontrolled, but otherwise disperses 10 minutes after you summoned it.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, you summon a second swarm at a point within range.