The night harbors many dangers and brings forth endless creatures with malicious intent. While those monsters are not often interesting by themselves, the things they carry with them are usually much more desirable. Unfortunately, those creatures either avoid daytime completely, or act friendly when under the light of day. Illumination Powder, if darkened sufficiently with additives, could be used to encourage these hostile monsters to spawn.
While a block can be right-clicked to create this field of darkness for a few seconds, creating such an area in close proximity might not be a great idea. The powder can be thrown, much like the Illumination Powder, to create this darkness wherever it lands. Due to the concentrated effect the powder creates, placing them too close together minimizes their efficacy.