The Staff of Famine is a black wooden staff that is capped with the withered corpse of an infant. The corpse has many trinkets and charms tied to it, a morbid mixture of funerary offerings and necromantic decoration.
To craft a staff of famine, a necromancer or other evil aligned sorcerer must take a length of wood suitable for a staff from a suitably tainted source. Trees killed by blight or drought are best, but wood harvested from cemetery trees or from a gallows will suffice if no other wood is available. It must be ritually cleansed, shaped, and then consecrated to the forces of darkness and decay. The grim topper is not a victim of murder, the infant corpse required for a staff of famine must be stillborn. The trinkets and doodads added later are mostly for cosmetic effect, but especially vile or evil decorations can improve the overall power of the staff.
A Staff of Famine acts as a Evil Wizard Staff, and can be used as a battery for magical power, and as a spell adder, allowing the necromancer to cast spells more efficiently or with greater force. This power can only be used for negative and evil spells. The Staff can also be used to create a Barrier vs Good, to protect the staff bearer from paladins, holy mages, and the like.
The Horrific Power of the Staff of Famine is that it can be used to cause a literal famine. This power can only be invoked once in a celestial year. The sorcerer in question must discharge his entire complement of spells into the casting, and then must also make a constitution check due to the force required for this virulent spell. The difficulty is quite high, and the caster can then divide their successes into effectiveness and area.
Stillborn - All creatures must make a check against the effectiveness of the spell to reproduce. Creatures (including all mortal and sentient races) that fail this check suffer miscarriage or stillbirth. This can decimate communities dependent on ranching, and livestock. Likewise, hunting communities can see their prey stock deplete and throw them into a winter/spring famine pattern. This also can remove a large portion of human and other mortal race births, hitting communities where they can be the most vulnerable, their offspring.
Crop Failure - a percentage of the crops in the affected area simply fail, or the plants are much less fruitful. This can range from a complete and total blight, to large fields performing poorly. Either way, the amount of food available is drastically reduced. In places where there is not an abundance, this can lead to serious food shortages, famine, and death. Lacking sufficient food stores, armies cannot fight, campaigns cannot be waged, and the chances of the common folk rising up against the nobility increases.
Arsenal of Evil - a necromancer's agents have been scouring the countryside looking for a stillborn child. The big bad is looking to make one of these staves, his undead host doesn't need to eat, and every corpse just adds to his potential army.
Recovered from Darkness - an aspiring warlord has gained one of the staves, and is looking for a sorcerer to power it, ready to sack the region for his own gain. PCs are hired to take him out and destroy the staff.
Collectables - a kooky wizard hires the PCs to recover this staff for his collection of staves. Neato!