Immortal-Killer

is a hidden Noble Phantasm of Xu Fu that ended as an incomplete product as a sublimated Noble Phantasm. Though she failed to achieve its completion, her accumulation of all forms of death allows her to "confer death to any organism by reducing the possibility of survival to the minimum." This ability lacks effectiveness against particular targets, such as "those never fated to die," "those related to the netherworld," and other such beings.
The Magi of Mt. Hourai sought to complete Xu Fu's research over a period of 2200 years. They managed to prove the concept, but failed to complete it before all dying out. With a Holy Grail to create a Micro-Singularity around Mt. Hourai, Xu Fu created the that could kill even the immortal Yu Mei-ren.
==References==
Category:Noble Phantasms
Category:Anti-Unit Noble Phantasms
Category:C+ rank Noble Phantasms
Category:Noble Phantasms introduced in Fate/Grand Order