The Oathpact was a voluntary agreement between the ten Heralds. The details of the Pact have been obscured, but it seems as though the Heralds were granted their Honorblades in return for their agreement to lead humankind against the cyclical Desolations that ravaged Roshar since humankind was exiled from the Tranquiline Halls. The Oathpact required that the Heralds return to an unnamed place of torture (probably Damnation) of their own free will when the Desolations were past; if they died while fighting in one of these battles, they were automatically returned to the unnamed place. At Aharietiam, the Last Desolation, the nine surviving Heralds chose to end the Oathpact, leaving their Blades behind. Only Talenel was killed and returned to the unnamed place. Due to his continued participation, the Oathpact remains somewhat intact and functioning. The other Heralds, presumably immortal, remained on Roshar and vowed not to seek each other out.
It has been explained that Damnation is a place where the vengeful souls of the ancient Dawnsingers who were slaughtered by humans reside, unable to pass on, and during a Desolation are empowered by Odium to possess Parshendi and reincarnate as their "gods." In between Desolations, it is these souls who torture the Heralds, venting their anger and rage upon them until they return to Roshar.
It has been theorized by the reader/contributor Siibt that the Oathpact bound Odium by allowing him to focus his hatred on the Heralds. This is supported by the following:
- In the The Way of Kings, the Herald Kalak comments on the place the Heralds go in between Desolations: a place where they are tortured.
- By torturing the Heralds, Odium was allowed to focus all hate and malice on the Heralds and not mankind.
- When the Heralds no longer could bear the pain of torture, they were released to Roshar where Odium would come against mankind in an attempt to destroy it.
- However, after being defeated, the Heralds would return to Damnation, presumably where the cycle of torture would continue.
- The Herald King, Jezrien, commented that the Heralds chose this burden willingly, so it can be assumed that Honor asked this of them in order to prevent the destruction of worlds by Odium.
- By abandoning the Oathpact and leaving Talenel in Damnation, Odium was still bound to the Oathpact and to torturing this Herald over the millennia and the Desolations were thought finished.
- At the end of The Way of Kings, however, Talenel comments that HE has failed, possibly meaning that he could no longer bear the burden that the nine others in torture chose not to and, therefore, left Damnation to start the Desolation or was expunged from Damnation, thus freeing Odium to once again potentially destroy mankind.
- Further evidence of Talenel holding back the Desolation by being tortured in Damnation is from an epigraph from Words of Radiance, part of the Diagram. "... The Desolation needs no usher ... spren anticipate it doing so soon ... . The Ancient of Stones must finally begin to crack (meaning, he can no longer bear the torture and his will to fight and hold back Odium and the Desolation has finally been subdued). It is a wonder that upon his will rested the prosperity and peace of a world for over four millennia. (This late sentence is a clear reference to Stonesinew in Damnation, as it has been 4500 years since nine of ten Heralds abandoned the Oathpact. Talenel has been holding back the Desolation through sheer will in torture for 4 millennia but no more).