Learn ‘Undo’ First

You find a box in the attic.

A magic wand rests in a case lined with red felt.  A classic wand — black shaft, white cap, forearm’s length.  Tapping something (or someone) with this wand while shouting “ka-ZAM!” will make that thing (or person) disappear.  There is no obvious way to bring back anything which has been thus dematerialized.