You pull fear and disgust from deep within, focusing it on the core of one living creature. You create a horrible visage that shocks the creature to the core and must pass a Constitution saving throw or be sent into a rabid fury. Each time the target takes damage, it can repeat the saving throw, ending the effect on itself on a success.
As a side effect to the fury, if possible, the creature will spend its bonus action to bite a non-infected target within melee range. On hit, the infected creature makes a constitution roll, and the defending creature makes a constitution saving throw. If the defending creature fails the throw they become infected as well.
Whenever the affected creature chooses another creature as a target, it must choose the target at random from among the creatures it can see within range of the attack, spell, or other ability it's using. If an enemy provokes an opportunity attack from the affected creature, the creature must make that attack if it is able to.
Creatures make a constitution saving throw at the end of their turn to see if they are still affected. You can only be affected by the spell once per combat.
At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the original save difficulty is increased by 1 for each slot level above 3rd.