At the rate of killing 100 blood beasts per day, it will take her 274 years to kill 10 million of them. This is clearly a very long time.
He was willing to wait for nearly 300 years of time for her to become an angel of killing. But Legion suddenly appeared and threw his plans into disarray.
Legion is clearly not a good target to possess because they have a lot of spiritual energy and can outlast him in the struggle for their body if he tries to possess them. But Legion should have become vulnerable after becoming an angel of killing.
Legion should be fighting with their avatars now in the struggle to become a complete angel of killing. So if he decides to possess Legion now, Legion won't be able to resist him because they have to resist the other clones.
Unfortunately, even if he succeeds, what he will get is an unfinished product that will be incapable of helping him advance and assimilate the Ocean of Blood.
