Unless you guys deliberately let him out, I really don't know if he'll emerge more than two or three times in this entire campaign. You would have to throw yourself into suicidal situations on a near-perpetual basis.
"Throw ourselves into Suicidal Situations".
Except, you know, this denies us all of the useful assets we acquired throughout the Prelude, except at the largess of Odyssial (Who is not interested in being subservient), and that he is so overwhelming that even a mote of his being would be likely to crush Ulyssian's spirit without mercy.
That, and we don't need to "Throw ourselves into suicidal situations", they'll
Happen by dint of "You exist, and bear Odyssial's Exaltation"
There is no inner conflict. Odyssial doesn't 'fight' Ulyssian. He's just a different way Ulyssian sometimes is. It's like Past Lives.
Bullshit and you know it, he doesn't need to "Fight" Ulyssian because it'll be a
Stomp, once he has enough influence, he'll just straight up mindbreak and take over, by word of Rihaku.
It's gaining an "I Win" button and a modest influx of experience, but gives us nothing to survive our present situation except diving into the Odyssial Button, and once we've started that chain, he's got a toehold, and when he has enough influence, he wins, full stop, we won't even be able to slow him down for nearly a hundred years.