First Sun Xibalba

is the Noble Phantasm of Tezcatlipoca.
First Sun Xibalba.
Originally, “Nahui Ocelotl” or “Mictlan Xibalba” would be correct, but this is Tezcatlipoca's style, in his modern day-obsessed state.
A fusion of the power of the age of the First Sun (Nahui Ocelotl) when he was the Sun in the skies, with his Authority as the ruler of Mictlampa, the paradise of rest, which is the subterranean underworld Mictlan, further identified as being the same as the underworld of Mayan mythology, Xibalba.
He rules over all the physical laws of this world, and all things must obey the natural laws as he decides they are, but he too is bound by the influence of his own divine providence.― Since the age of the First Sun, in which the now-perished giants roamed freely, left its traces behind only in the underworld, recovering that power, or otherwise making it appear in this world, is necessarily equivalent to the underworld itself coming into existence in the world.
Black Tezcatlipoca is an almighty deity who manipulates all creation, however, his Authority doesn't allow him to create whatever he wants. It can only "manifest anything that could possibly happen within [his] set of rules". If something will happen in the future, then he can slide around the order in which it comes to pass. This is not indefinite, there is a time limit to how long the effect lasts before the timeline returns to its correct order. 
While bound by Human flesh, Tezcatlipoca can't use this Authority without the support of one of Daybit Sem Void's Command Spells. In exchange for sacrificing his two lungs, he summons the solar eclipse with which he activates his Noble Phantasm.Fate/Grand Order: Cosmos in the Lostbelt - Nahui Mictlan: Golden Sea of Trees Travelogue - Section 10: The Day of ORT
==Development==
The giant "skeleton mecha" in this Noble Phantasm's animation was originally designed by Tajima Shou as a Third Ascension design for Tezcatlipoca. Because it was way too big to use as a playable Servant Tajima was asked to make a different design, but the "skeleton mecha" was repurposed for his Noble Phantasm.Famitsu - Fate/Grand Order 8th Anniversary interview with Kinoko Nasu and Takashi Takeuchi translated by ComunCoutinho at Reddit
==References==
Category:Noble Phantasms
Category:Noble Phantasms introduced in Fate/Grand Order
Category:B rank Noble Phantasms
Category:Anti-World Noble Phantasms
Category:Divine Authorities