Hadzutsiqsamûr Aikorjontû

Hadzutsiqsamûr Aikorjontû, a Sith language compound word roughly translated into Galactic Basic Standard as "birthing a demon of flame by means of blood," was a sacrificial ritual of Sith magic developed by ancient Sith sorcerers millennia prior to the birth of the Sith Empire that summoned an unstoppable physical manifestation of the dark side of the Force at the cost of an indeterminate number of the caster's midi-chlorians.

Ritual
The Hadzutsiqsamûr Aikorjontû ritual was similar in many respects to the simpler Dwomutsiqsa incantation of Sith magic used to summon a Smoke Demon. When properly invoked, Hadzutsiqsamûr Aikorjontû summoned a semi-sentient manifestation of the dark side that took the form of cursed fire twisted into the vague likeness of a humanoid of indeterminate species. The entity was fully capable of disintegrating any physical material in its path, including cortosis, phrik, and Mandalorian iron. Apart from a handful of exceptions, the entity could not be banished by conventional counterspells by any apart from the original invoking sorcerer. However, this dark-sided construct required great strength of will on the part of the caster to command and direct as desired, as its default behavior was to destroy anything in its immediate vicinity without discrimination.

The summoning of the dark-sided entity required a blood sacrifice on the part of the caster that sacrificed the life-force of an indeterminate number of midi-chlorians, thus reducing the caster's Force sensitivity by a tangible degree in perpetuity. As a result, the incantation, though considered one of the most powerful secrets of Sith magic, was viewed as a weapon of last resort by Sith sorcerers and rarely invoked except at the utmost end of need.

Behind the scenes
Hadzutsiqsamûr Aikorjontû, its incantation, and the details of its physical manifestation were inspired by the "Fiendfyre" and "Patronus 2.0" spells as they appeared in Harry Potter and the Methods of Rationality.