Poisoner Mastery

You are skilled at with the subtlety of poisons, causing untold destruction. You gain the following benefits:

• When determining the save DC of a poison you control, you can use 8 + your proficiency bonus + your Intelligence modifier, if it would be higher than the item's DC.
• When you apply a poison to a weapon or ammunition, that poison can affect an additional hit or an additional piece of ammunition.
• Creatures suffering from the poisoned condition have disadvantage on saving throws against poisons you control.
• When using a poison that requires a saving throw and deals damage, you can take a penalty to the save DC equal to your proficiency bonus. If you do so, the item's damage increases by an amount equal to twice your proficiency bonus.