Anti-Magic Gas
From DALpedia
Anti-Magic Gas or Anti-Mana Gas is a special type of gas that disables all exterior magic abilities from being used, and other spells such as teleportation. However, some magic can be used in this gas. Transformation, low powered self-healing spells and a few sense heightening spells can still work to a certain extent, yet they may be dulled.
The gas is usually stored in dungeons with high security, such as the prison in Bandervil the fortress of Lizaberg and a few prisons in Kandarin. The gas can also be stored in small bombs, and can be used to temporally disable the magic abilities of a mage if thrown at them. This type of weapon was used by Jonny Albatrash of the Crimson Empire "Tax Collectors".