Curse Of Spreading/Potion Of Spreading

The curse of spreading would turn any hostile mob into a zombie form when hit. Such as zombie creepers, spiders, and so forth. (Not mobs that are already undead, though.) This is only a sword enchantment however and can only be found in treasure chests. Or, if you want, you can zombify your enemies from afar using potions and tipped arrows of spreading. These are very rare potions, because to make one, you need to smelt a sword enchanted with curse of spreading in a furnace to obtain a cursed nugget, then filter that into an awkward potion. (And you can only smelt a sword enchanted with this curse, or it will just turn out to be a normal nugget. And you can only use  a gold or iron sword.)