Delvar's Carrion Call

In the palm of your hand, you present the feather of a crow, or the tail of a rat. Uttering blasphemous incantations of plague and pestilence, the offering bursts into a sickening green flame. Ghastly black smoke billows up from the accursed flames, and out of the smoke pours a writhing tide of vermin, or a maelstrom of screeching fowl.

A massive swarm of crows or rats (Depending on the material component offered), appears in a 20-foot radius sphere within range. The swarm spreads around corners. Additionally, while you are concentrating on this spell, you can move the swarm up to 20 feet within range as a bonus action.

Flock of Doom:  The flock of crows can be moved in any direction, and the area within the flock is Heavily Obscured. Creatures within the flock that rely on their ears for hearing are deafened by the cacophony of screeching crows. Creatures that start or end their turn within the flock must make a Dexterity saving throw, taking 8d4 Piercing damage on a failed save and half damage on a successful save. Creatures must also make a Wisdom saving throw. On a failed save, the creature is Frightened until the spell ends. The Frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Vermintide: The area within the swarm of rats is considered Difficult Terrain. Creatures that start or end their turn within the swarm of rats must make a Strength saving throw, taking 6d6 Piercing damage on a failed save, or half as much damage on a successful save. Creatures must also make a Constitution saving throw. On a failed save, the target is Poisoned, and takes 1d6 poison damage at the start of their next turn until the Poisoned condition is removed. The Poisoned target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.