Magic Item of the Week - Bag of Encumbrance

  My oldest son, who is 19, has been running a game of AD&D 1e for a few months, now. All of his players are first-timers who never played before they sat down with him. One of them, Daniel, was having encumbrance explained to him when he said,

"Oh, I get it. Man, I wish I could just... throw encumbrance on an enemy!"

  I love the perspective new players have!
  This led my oldest and I to joke around until we came up with - the Bag of Encumbrance.
  The bag appears to be an unremarkable jute bag full of a strange red-brown dust, about the consistency of fine wheat flour. No matter how much dust is inside the enchanted bag always weighs/encumbers as 5 lbs.
  Once per round the owner can reach into the bag, pull out a handful of the dust, and hurl it at a foe. The dust 'hold together' almost like a snowball until it strikes a solid object and has ranges of 2"/4"/6".Since the dust is not stopped by armor only dexterity and magical bonuses affect armor class.
  Example: Jerczy was doing well, but the enemies were too many. Inghemar reached into her Bag of Encumbrance and tossed the dust at the half-ogre. The half-ogre was in +3 plate mail, normally A.C 0 but only the bonuses mattered - she rolled against A.C. 7.

  Any creature struck by the Dust gains a "level" of encumbrance that reduces their movement rate 1/4th of their unencumbered maximum. A human with a base movement of 12" now has a max base of 9"; if they were already in plate mail and carrying a lot of gear so that they were at a maximum of 4" their new movement would be 1". Creatures with magical movement (such as Boots of Speed) use their magical top speed as their base movement.
  At two "levels" the target cannot fly (naturally, by spell, or by item), swim or effectively jump more than half a foot vertically. When movement is reduced to 0" or at 4 "levels" the creature collapses, immobilized by the magical weight. The magical encumbrance can cause no direct harm, although a target may drown, be killed while pinned, etc.
  Target can drop equipment, remove armor, etc. to reduce natural encumbrance. Even at a movement rate of 0" this can be done at half the usual speed. Regardless of actual encumbrance a creature affected by 4 or more "levels" of magical encumbrance will remain immobilized.

  The Dust will slowly sift off of a target and each 'dose' ceases to affect its target after 2 turns. Wind and water have no ability to remove the Dust but a cup of vinegar will rinse off a dose of the Dust in just 1 segment (up to a quart may be applied as a single action, if desired)

  When the Dust is removed from the bag its magical properties briefly affect the wielder as the Dust is hurled, making its use exhausting. The Dust can only be hurled every other round and if hurled in 4 of any 12 rounds the user must rest for a turn before running or fighting.

 When a Bag is found it has 1d6+4 uses of Dust inside. If the Dust is placed into any container but the appropriately enchanted Bag that container immediately has the full amount of encumbrance of the dust inside. Also, once removed from the Bag the Dust loses its potency after just 3 days.

  Legend states that the Dust is made from a rare ant found only on the Plane of Earth.