WARNING: The following contains spoilers for Jujutsu Kaisen Chapter 179 "Sendai Colony, Part 6," by Gege Akutami, John Werry and Snir Aharon, available in English from Viz Media.
Jujutsu Kaisen's Cursed Techniques are among the most complex and entertaining power systems in anime/manga. One of the best aspects of this particular system is the ability to use Domain Expansion, said to be the peak of Jujutsu Sorcery. It's not a common skill among Jujutsu society, although recent events in the Culling Game may have fans thinking it is.
Some of the most skilled sorcerers, like Kento Nanami, haven't been able to reach this level of Sorcery. The fact that the Culling Game has already shown five different characters cast their Domain Expansions (or at least attempt to) is more a testament to how powerful these players are. A sorcerer using their Domain Expansion usually means victory, thanks to their attacks hitting the target being guaranteed. However, not all Domains work like this, as seen with Hiromi Higuruma's Deadly Sentencing.
When two sorcerers cast their Domain Expansions in the same space, usually the more powerful Domain will overwhelm the weaker one. The latter will ultimately break and only the stronger one will remain. Gojo Satoru proved this in his fight against Jogo. However, it gets a bit more complicated when it's three Domains instead of just two.
In Chapter 179 of Jujutsu Kaisen, Yuta, Uro and Ishigori all try to cast their Domain Expansions at the same time -- and it doesn't go as planned for any of them. When Domains overlap, the can't-miss attacks actually cancel each other out. Moreover, as they attempt to erect their barriers, the required internal and external conditions required differ for each one. As if that didn't make the situation difficult enough, an unexpected invader suddenly intrudes.
Kurourishi had apparently reproduced by parthenogenesis before Yuta killed him in Chapter 175. After the original was exorcised, the Cursed Energy of fear throughout Japan was poured into the child. Thus, a new Kurourushi -- just as strong as the previous one -- was created. Its sudden invasion into the clashing Domain barriers, combined with their differing conditions, causes all three barriers to completely break.
No new Domain Expansions were actually seen in Chapter 179, but Jujutsu Kaisen readers still learned some new details. Interestingly, this new information does raise a question regarding Sukuna's Malevolent Shrine, which is unlike any other Domain Expansion seen so far. It doesn't create a separate space using a relatively small barrier but instead covers a radius of nearly 200 meters. What would happen if Sukuna's Domain Expansion clashed against two others? It seems plausible to assume that his would easily overwhelm any others, but this remains to be seen as the manga continues.
