This is either a tool of assassination, or a horrid curse, depending upon how it is used. This item appears as a somewhat battered copper drinking cup. It will radiate magic if tested for. This cup looks somewhat old, but in reality, it is quite ancient, hailing from a time when political intrigue and quiet assassination among elite members of society were distressingly common. Many items with similar powers were in circulation back then, but this cup, in specific, was created by a nervous, conniving wizard, for their own personal use.
Early investigation will reveal that it has the ability to automatically cast Neutralize Poison on any liquid poured into it. The surface of any such liquids will glint reddish-orange for a few moments, as if reflecting a spectacular sunset, indicating that they have been cleared of any toxins or poisons.
The curse comes in when other drinking cups, bottles, or even wine skins are placed within twenty feet of it. The beverages in these containers will all glint bluish-green for a few moments, as if reflecting the ocean on a beautiful day, indicating that they have all been poisoned. Magical liquids, such as potions, get a Saving Throw vs Magic. This poison is a fast-acting, requiring drinkers to make a Saving Throw or begin losing 1 HP per minute, until dead! A successful Save indicates the drinker has resisted the poison, though they will still weak for 1d6 hours afterwards.
If a liquid that has been poisoned by being in proximity to this cup is then poured into it, it will be neutralized, as normal. If it is not consumed directly from the cup, however, it will simply become poisoned again, once it is poured into another vessel. If a successful Remove Curse spell is cast directly upon the cup, it will halt its poisoning power for 1 day per level of the caster, after which time it will begin poisoning liquids again. The Neutralize Poison power remains unaffected.