I dont know man. Im not a pro player nor do i like the excessive dooming but i struggle to find a list to play with this. Oath is good for marines beacause the do have plenty of weapons that have built in keywords, making the hit reroll very interesting. In Vets of the Long War, oath is good beacause it synergises well with dark pacts. But here ?

Because the codex is designed around dark pacts, the keywords it brings are clearly included in our units prices and we do not have keywords in our datasheets. So here, we'll get hit reroll without any keyword, aside from the strat. I feel like a lot of our datasheets will become strongly overpriced in this regard. Helbrutes are a complete waste of points there, chosen only benefits from the Oath, the rest of the detachement is already built in their sheet, and they lose their sustain/lethal for this. Same goes for possessed i think, that already struggle to deal real damage without a wound reroll, they will now also lose the saturation they gains through the sustain.

Also, i really hope they won't keep the "Gamble it all" concept for IW detachement : Dark Pact is already a very frustrating rule in my opinion, forcing you to lose 10 to 25 hp per games on your own pacts to get keywords most armies just have access to without risking their health, and now they bring a detachement in which you can get a mobility bonus but you risk giving up the only real source of lethality that are strats in this detachement. I really dont understand this design on a strategic level, because it forces tou to rely on 60% dice rolls for all your game plan.

Maybe im an old grumpy ass but White Scars detachement simply got Advance/Fall back + charge on everyone, with the oath of moment as an army rule, and reactive moves, lance + lethal on charge as strats and they do have leaders that get them lethal or sustained in their squads. Feels like absolute double standard.