I'm not sure how I feel about Deathblade. He's not Nighthawk and black's three drops are decently stacked, but the ceiling feels high on this guy and I love graveyard shenanigans.... Just not sold yet.
I don't run Containment Priest because I've never been comfortable running a hate card that completely hoses so many interesting strategies, but a cantriping one shot version sounds a lot more appealing. This counters any reanimator spell, token making spell, any variety of Natural Order effect, an activation of Pack Rat, this actually feels maindeckable because even RDW makes tokens sometimes, even Ux control occasionally drops a Battlesphere, minuses an Ashiok or casts a Bribery. The more I think about it, the more I want to be drafting it right now.
I hate hosers like this. If you want to hose people, use a counterspell or removal spell instead. I see no reason to punish some of the hardest-to-assemble decks (Reanimator & Kiki-combo in particular) for a lousy cantrip effect, and if tokens are an actual threat in your cube worth maindecking this jank and holding up 2 mana for a T2 Raise the Alarm, you have severe balance issues that this won't band-aid for. I already run few tokens myself because most of them are so boring, and if Pack Rat needs policing (hard to fathom given how slow it is in most cubes), give white another solid removal spell that comes down earlier. When I see cards like this in cube, I don't bother trying to assemble something already delicate like Kiki-combo or Reanimator, because someone who last-picked the hoser is going to eat my ass in the most unfun way possible. Either decrease your tutor effects (I'm a big advocate of going tutor-light) or increase removal/counterspells, but please, do NOT put hosers like this in your cube unless you want to severely harm the more exciting, hard-to-craft decks available for the sake of a cantrip that does not interact effectively with the majority of the decks that get made in cube.