Eighth Doctor's regeneration

Though there existed multiple possible ninth incarnations of the Doctor, (PROSE: The Gallifrey Chronicles, The Tomorrow Windows) one account held that the Eighth Doctor regenerated into the War Doctor with the assistance of the Sisterhood of Karn during the Last Great Time War, having been killed when Cass Fermazzi's gunship crashed on the planet Karn with him aboard. (TV: The Day of the Doctor) This was the eighth regeneration of the 12-regeneration life cycle beginning with the First Doctor. (TV: The Time of the Doctor)

According to another account, the Eighth Doctor regenerated into the Ninth Doctor after using the Moment to destroy Gallifrey Original. (PROSE: Doctor Who and the Time War)