Potion of Poison

This concoction seems to be a Potion of Healing, however, it is actually poison.
An Identify spell reveals its true Nature. If you drink it, take 3d6 poison damage, and make
a DC 13 Constitution saving
throw or be Poisoned. At the start of each turn, while Poisoned, take 3d6 poison damage.
Save at the end of each round in order to reduce damage by 1d6 until damage is 0