Theoretically, there might be no upper limit to the number of Grand Priests and Zenos—or rather, that limit might be so high it was impossible to quantify, much like Zamasu, who could split endlessly.
Even the Grand Priest probably could not have imagined such a move. At most, he could think of summoning himself from parallel timelines, which was why the Dragon God's side had a pair of Grand Priests and Zenos.
The natives might not have thought things through so thoroughly, but Aizen had to. Otherwise, if they just let Lu Li charge in recklessly, they would be utterly doomed this time.
Thus, from the very beginning, he had considered that in the worst-case scenario, they would not be facing only the Grand Priest and Zeno of this world, but an unwinnable situation.
To prevent that from happening, the research Aizen had conducted in Subspace over the years had not been on a device to strengthen himself, but one capable of sealing off travel between parallel worlds.
He had not told Lu Li about it, mainly because Lu Li had been too focused during that period and he did not want to disturb him. Besides, Aizen felt this was the job of the strategist and not something Lu Li needed to worry about.
Likewise, he had not told Soul Singer or the other members of this operation, because Aizen did not trust them.
After all, if there was only one Zeno and one Grand Priest, there was still a chance of survival with the power he and Lu Li had fused. But if there were infinitely many Grand Priests and Zenos, then even freeing the Dragon God would only lead to death.
In this operation, Aizen could tolerate traitors appearing, since human behavior was uncontrollable. But he would never