Muggles' Guide to Harry Potter/Magic/Descendo

Overview
The Descendo jinx is used to knock over piles of things. It is apparently not an instantaneous action; using it on a tall pile of stuff, for instance, will cause the pile to start to fall, but it can still be stopped with a properly timed Finite charm.

Extended Description
We first see this jinx used near the end of Harry Potter and the Deathly Hallows. Harry, Ron, and Hermione have entered the Room of Requirement, and have split up to search for the lost Diadem. Harry is trapped by Draco, Crabbe, and Goyle. Hearing Ron, Crabbe uses the Descendo jinx to try and drop a 50-foot pile of stuff onto Ron; Harry stops it with the Finite charm, and Draco then prevents him from using it again.