The Deadweight Spell (incantation: feordupois) is a spell that causes the target to become too heavy to move. There is a counterspell, but its incantation is as yet unknown; it is possible that the Featherweight Charm may be useful in counteracting the Spell.
In September 2009, Quick again used the spell against Benjamin Rash while dueling him and his brother. Professor Mary Shirtliffe later refered to the spell as the Deadweight "Jinx," and asked Quick where she learned the incantation. Mage-Sergeant Major Eric Strangeland later cast Deadweight Spells on his fellow JROC members during Deadweight Drills. Quick avoided the effects of the Spell by surreptitiously using the counterspell.
In January 2011, Quick cast the spell at least three times against a Dark creature that she confronted in Manuelito's home outside Orange Rock in New Mexico. She later used the spell against a pack of seven werewolves that were pursuing her, John Thompson, and Patricia Peshlakai as they ascended Witches' Rock.
The incantation may derive from the French phrase "fardeau du poids," which translate to "burden of weight."