Doom of Serpent Coils

You drink a dose of venom or other poison and spread the effect to other living things around you. If the poison normally allows a saving throw, your save automatically fails. You suffer the effect of the poison normally before spreading the poison to all other living creatures within 10 feet of you. Instead of making the usual saving throw against the poison, each creature around you makes a Constitution saving throw against the spell. On a successful save, a target suffers no damage or other effect from the poison and is immune to further castings of doom of serpent coils for 24 hours. On a failed save, a target doesn't suffer the poison’s usual effect; instead, it takes 4d6 poison damage and is poisoned. While poisoned in this way, a creature repeats the saving throw at the end of each of its turns. On a subsequent failed save, it takes 4d6 poison damage and is still poisoned. On a subsequent successful save, it is no longer poisoned and is immune to further castings of doom of serpent coils for 24 hours.

Multiple castings of this spell have no additional effect on creatures that are already poisoned by it. The effect can be ended by protection from poison or comparable magic.