First, the enemy's main force could not be on Earth. That much was known.
Kamar-Taj and the Sanctum Sanctorum's defenses could not be guaranteed to be one hundred percent without flaws, but they were 99.99999% reliable. As the Sorcerer Supreme, Su Ming dared to say that—especially with Ancient One still on Earth.
Earth was too small, after all. There were too many powerful figures hiding there, along with the Eternals' own faction of compromisers. It would be inconvenient for them to do anything.
That meant the black-robed figures had to be somewhere in the universe, beyond the multiverse, or within some dimension.
The next possibility to eliminate was a dimension. Every known dimension in the Marvel Universe currently had an owner, and it would not be convenient to secretly commit evil deeds right under someone else's nose.
What if they killed a Dimensional Demon God and took over its dimension?
The odds were too low. Dimensional Demon Gods were called demon gods not because they had fallen to demonic corruption, but because they all wielded various forms of magic.
Every demon god that had survived until now possessed exceptional means of escape, all powered by the energy contained within their dimensions. Celestial technology and Eternals' divine power could not affect them at all.
Even taking a step back, even if the black-robed figures had truly killed some demon god, they could not disguise themselves as the victim to cover it up.
Once most demon gods died, the conceptual authority they controlled would immediately be released into the universe for newcomers to fight over. The vast majority of those on the Mystic Side would sense it—it would be practically announcing it to the world.
The next option to eliminate was that they were hiding beyond the multiverse. If they had that