Recent oath lists playing rune-scarred demon like this one have mostly been using it to set up a kill using underworld breach. Getting two pieces of the combo seems pretty good and can be fairly resilient letting you make a pile from breach, lotus, brain freeze or sevinne's reclamation depending on what you need/what you milled over with oath.
Its more of an esper mentor deck that I call doomsday for fun. Doomsday won me one game that was already pretty locked up, I almost had a turn two doomsday against smennen when he mulled to 3 but he hit multiple cabal therapies off some good dredges. It closes out the game fast when you've locked things up with teferi and narset and can be a surprise win game 1 that makes people board weird but it gets sided out in almost every matchup. Mentor is the main win I just really like the card doomsday and played it for fun. That said it makes sideboarding really easy since the doomsday package is usually about how many cards you want to bring in +/- a preordain.
That gush impression inspired an esper doomsday list I took to 3-3 in the challenge last week. It seems like the combo of lavinia and teferi is pretty powerful. Teferi definitely opens up a lot of interesting lines. Did you have a hard time playing leovold at all? DRS probably helps with that but what do you think about narset?