Malice of Arachia

The first of the Arachi developed a clever toxin that turns the weak upon their former friends.
You coat a weapon in a deadly enchanted venom. The first time this weapon inflicts damage to a creature, the venom enters the target’s veins, cursing them with terrible hallucinations and compulsions. The cursed target must make a Constitution saving throw at the start of each of its turns for one minute. Each time it fails, choose a creature within 5 feet of it that you can see. The cursed target uses its reaction to make a single melee weapon attack targeting the creature. Once it lands a successful attack caused by this effect, the effect ends. A creature that is immune to the poisoned condition is immune to this effect.

At Higher Levels: When you cast this spell using a slot of 2nd level or higher, the effect on the cursed target lasts for one additional successful hit using its reaction per slot level above 1st.