Revenant Incense

The Revenant Incense (also translated as Revival Incense) is a special type of restoration item used by Shiroe in order to temporarily reunite Rundelhaus Code's spirit with his body.

Overview
Revenant Incense is contained within a special incense burner and will turn a dead ally or creature into a special monster&mdash;effectively a zombie that can continue to fight&mdash;for three minutes. After three minutes are up, Adventurers affected by this item will die and resurrect at the Cathedral. Because of this, it is not considered a resurrection item.

Of course, for People of the Earth, they will permanently die after the three minutes are up unless an alternative means of revival is done.

Return of the Goblin King arc
While defending Choushi Town, Rundelhaus Code is mortally wounded and is about to die. Due to the fact that he is a member of the People of the Earth, he would not revive at the Cathedral, like the other Adventurers.

However, due to the efforts of Isuzu, Minori, and Serara, his body was restored, though his spirit was already gone. After Shiroe arrives, he first restores the party's MP (including Rudy's) using Mana Channeling, thereby forcing Rudy's body and spirit to reconnect. He then uses Revenant Incense to force Rudy's spirit back into his body long enough for him to sign a Contract, thereby giving him membership within Shiroe's guild and the subclass of Adventurer, which saves his life.