I'm thinking a combination of Morbid and Madness, like "Whenever a creature you controls dies, you may cast this card for its Spectacle cost". That would fit well with aggro and the Rakdos thematically.
Personally I would love if it was Morbid + Splice, but I don't really see that happening, even if you were limited to 1 Spectacle a turn.
Amusingly, Gather the Townsfolk gives you exactly five 1/1 humans to block those zombies...once.
Personally I would love if it was Morbid + Splice, but I don't really see that happening, even if you were limited to 1 Spectacle a turn.