A longsword of ophidian design. Its blade poisons the blood of its victims. It deals an additional 1d6 poison damage. (Creatures without blood don't take the additional poison damage.)

Once per day, as an action, you can use the blade to transform into a Giant Poisonous Snake, which is friendly only to you, for up to an hour at a time. This snake doesn't ever need to eat or sleep. You can use your action to share the snake's senses (you are blind to your own). You can distinguish this snake from others, and as a bonus action, you may grab the snake, turning it back into a sword. If an hour passes, it will automatically turn into a sword again.

If the snake dies, it transforms back into blade form as a Broken Viper Blade. A Broken Viper Blade cannot transform into a snake again, and its poison damage is reduced to 1d4.

Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Damage: Poison, Poisoned, Damage, Combat, Versatile, Sap