"He must have prepared this escape for a while," Death Reverence thought. Most of the Anti-Dao Matter was annihilated after the Lost Timeline, leaving only a few scattered pieces throughout the Infinite Trichiliocosm. As someone with the authority of [Heaven], the Heaven Cardinal is one of the few people who would know the location of the few remaining pieces.
However, for him to acquire it, a few things must have occurred. First, he should have hidden the truth from Grand Dao. From what Death Reverence knows, all individuals who have acquired Anti-Dao Matter must hand it over to the cardinals in exchange for a reward. If they don't, they will be hunted down. The second step is to acquire the material quietly and even utilize it while under Grand Dao's nose.
