I played around in every color but Black this week, and I did creatures and enchantments, so I set out to make a Black Instant for today's design. I initially though something along the line of
Persecute. I wanted removal that would prevent a player from casting cards with the same name for the rest of the game, but that ended up feeling more white, in the vein of
Exclusion Ritual. Tinkering around, I settled on the flavor of a dying creature becoming a martyr, and ended up with this: