Albus's Antimagic Apozem

This tempered glass, lead-lined vial has a bold "AAA" label on the front. It is filled with a clear, thin gel that gives off a strange odour of raw egg with metallic undertones. The gel was harvested from the primary eye of a Beholder. Anything it comes into direct contact with the gel is unaffected by magic and has magical effects suppressed, as per the Antimagic Field spell, for the duration of the contact. The gel is water soluble, meaning it can be easily rinsed off by water. Once removed from the vial, the gel cannot be reused.

Uses and interactions of the gel are subject to DM discretion, with some sample suggestions below:

Sensory

Pouring the vial onto a creature's sensory organ causes that creature to perceive the world as it is without any obvious magical phenomena. For example, when poured into:

• Eyes: magical flames, mists, and other visually apparent magics are invisible; things made magically invisible are visible
• Ears: magical sounds are undetectable, and magical silence has no effect
• Nose: magical scents are undetectable, and magical suppression of smells have no effect 
• Tongue: any magical influence on the creature's ability to taste, speak, lie, or persuade are suppressed.
  If the creature swallows the gel, they are subjected to the gel as an ingested poison (see below)
• Skin: they are considered to have been subjected to the gel as a contact poison (see below)

This effect lasts for the shorter of 1 minute or until flushed with water.

Poison

The gel can be used as a poison in different ways, per the below. A creature immune to poison is not immune to these effects.

Contact poison: a creature subjected to this poison cannot cause or be affected by any touch-based magical effect, be invisible or insubstantial, benefit from magical resistances, or perform magical movement of any kind such as flying, earth glide, or teleportation. This effect lasts for the shorter of 1 minute or until the gel is washed off with water.
Contact poison can be smeared on an object and remains potent until it is touched or washed off. A creature that touches contact poison with exposed skin suffers its effects.

Injury poison: a creature subjected to this poison must make a DC 15 Constitution saving throw. On a failure, it suffers the effects of the above contact poison and cannot cast spells or use any magical abilities for 1 minute. It can repeat the saving throw at the end of each turn, ending all effects on a success. Running water over the wound grants an additional saving throw.
Injury poison can be applied to weapons, ammunition, trap components, and other objects that deal piercing or slashing damage and remains potent until delivered through a wound or washed off. A creature that takes piercing or slashing damage from an object coated with the poison is exposed to its effects.

Ingested poison: a creature subjected to this poison must make a DC 19 Constitution saving throw. On a failure, it suffers the effects of the above injury poison for 1 hour. Thereafter, it is limited to a single magical action per round until it takes a long rest. Drinking water grants an additional saving throw, ending the effect on a success.
A creature must swallow an entire dose of ingested poison to suffer its effects. The dose can be delivered in food or a liquid. The DM may decide that a partial dose has a reduced effect, such as allowing advantage on the saving throw or dealing only half damage on a failed save.

Object interaction

The antimagic gel may be used to coat up to 8 square feet of flat surface area, i.e. a 2ft cube.

Any magical object fully coated with the gel has magical effects suppressed, as if under the effects of the Antimagic Field spell. This persists until the gel is washed off with water.

If the antimagic gel comes in contact with an illusion, that part of the illusion vanishes for the duration that the gel remains in contact. For example, splashing an illusory door would cause a visual effect momentarily resembling acid as the gel passes through the door, then the door would return to its untouched form except for the bottom where the gel has pooled.