Judith, the Scourge Diva is by far the most interesting commander out of Ravnica Allegiance, in my opinion. The only competition may be Prime Speaker Vannifar and Teysa Karlov . In my experience, PSV is a lower-energy, less-intense version of Yisan, the Wanderer Bard , and Teysa Karlov just makes for a less interesting deck than Judith does(still brewing it though!).
Sacrifice decks are harder in Rakdos than in Golgari or Jund. This is because Green is very good at generating tokens( Awakening Zone , From Beyond , Kessig Cagebreakers , Nissa, Voice of Zendikar , and many other sacrifice staples are Green). This is why we run cards like Krenko, Mob Boss and Legion Warboss . Goblin Rabblemaster would also be good, but he tends to make a lot of enemies by forcing you to attack. The good thing is, Rakdos keeps all the usual Black staples like Sadistic Hypnotist , Grave Pact , and Black Market .
So why Judith? After all, we can also run Wort, Boggart Auntie , Lyzolda, the Blood Witch , or Tymaret, the Murder King . The latter even comes with a get-out-of-commander-tax-free card! The reason for Judith is simple: Infect. Grafted Exoskeleton , Phyresis , even Tainted Strike can all kill quickly. There's no way we can keep our sacrifice engine going long enough to do 120 or even 75 damage. But 30 is very doable. Judith, unlike Tymaret, the Murder King or Lyzolda, the Blood Witch allows us to infect our opponents to death quickly and effectively.

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