The Aum Staff (オームの杖 Ōmu no Tsue, called the Ohm Staff in the Japanese version) is a powerful staff that can resurrect the dead. It appears in Fire Emblem: Ankoku Ryū to Hikari no Tsurugi and its sequel and remakes and can only be used on the final chapter. But with a single use. It's a staff to be used wisely. The character comes back with the same stats as they had when killed, but at full HP and free of status conditions. It originally could be only used by Elice, although in Shadow Dragon and Shin Monshō no Nazo ~Hikari to Kage no Eiyū~ it can be used by the other princesses (Maria, Minerva, Yumina, Nyna, Shiida, and Sheema) as well, if they are the right class.
It cannot be used to bring back the character which was used as a decoy in the prologue of Shadow Dragon, because according to Shin Monshō no Nazo ~Hikari to Kage no Eiyū~, Jiol's army in the prologue did not kill that character.