Skirmish at the Marble Staircase

In this skirmish, several duels were witnessed by Harry, Hermione and Ron as they crossed the marble stairs.

These duels were:
 * Filius Flitwick against Yaxley, the Death Eater fell with a scream.
 * Dean Thomas to Antonin Dolovoh, Dolovoh is petrified by Parvati.
 * Parvati Patil against Travers.
 * Peeves against the Death Eaters, launching pods
 * snargaluff.

A little later:

In the Film:
 * Sybill Trelawney and Hermione against Fenrir Greyback, in protection of Lavender Brown
 * Voldemort and Harry, before fighting in the entrance courtyard, fighting briefly in the stairs.