Bladegriff Prototype isn't bad, but its effect doesn't always help you as much as it helps others, and once a multiplayer game is down to two players, it's basically just your opponent sacrificing permanents, which might not be that impactful in the late game
Surveil cards away with the likes of Doom Whisperer and Case of the Shifting Visage, both to grow Mirko and get reanimation targets in the graveyard
There's also some good Golgari ways to get creatures into your yard and so this is an okay enabler/payoff
A few cards have already stood out, benefiting from their legality, be it as commanders, combo pieces, or just a weird on-off trick
For this reason, the best Omo deck is probably only built around one or two basic land types instead of all of them