Implement of Malice seems to do something similar to Mind Rot, while being more mechanically interesting and enabling Revolt. It's the worst common in black in the set, and balancing the curve a bit with a decent common seems like a better inclusion. If I go up one more common, it needs to be a non-creature spell.

Preemptively, the cards we'd add are:

Caught in the Brights
Hightide Hermit/Bastion Inventor
Spontaneous Artist
Tidy Conclusion
Prey Upon