In order to prevent the invading Undead Army, the 7 united races of Andalucian continent launched an all out offensive to defeat the Lich King. On the brink of death, Sema Ainsworth cast a forbidden spell with the intent of taking the Undead king along with him to death.
The forbidden spell sent him to the past before the invasion happened. Waking up with memories of the future fully intact, he takes advantage of this chance and decides to prevent the upcoming tragedy.